Tanks and Grow Media

If I only knew then what I know now...

I like these troughs I found at Tractor Supply.  They are a bit shallow, but I think they will do very well.

Heres an update to my expansion using bunk feeders.

Im seriously considering this long one (approximately 10"Dx24"Wx108"L) for a grow bed.  $154.00

These would make a nice fish tank.  The big one is about 300 gallons. 5Dx3H  $250.00

After building my own tanks from both 45mil EPDM and the pond liner they sell at Home Depot I would lean toward these heavy duty Rubbermaid Structural Foam Stock Tanks, because they are less likely to leak, easy to clean, easy to insert bulkheads into

I have also built an IBC system.  But polyethylene is not UV proof.  This round tank appeals to me because it would be less difficult to manage than a 4 deep IBC fish tank.   

My relentless quest for a reasonably priced media has finally turned up Pumice.

UPDATE 12/3/2012
Pumice has turned out to be a great media for net pots, but it packs, and I believe it would tend to clog if used in an aquaponic media bed where the purpose of a media bed is to filter the solids.  It might be acceptable in a hydroponic or bioponic system where solids are not an issue.

The pumice I bought looks exactly as in the picture.

The size ranges from about  3-8 mm.
The pieces are very hard and do not easily crush.

I crushed a piece with a pair of pliers.  Then I rubbed it between my hands.  Some particles first appeared to be long and pointed, but the rubbing caused them all to break down into irregular grit.  There were no sharp shards left in my hands afterward, and nothing that looked sharp remained.  It tends to form roundish particles.

Its extremely easy on the hands.  Its soft on the skin and nails; not at all like feather rocks or lava rock.  There are no shape shards, and if it brakes I doubt that it would create sharp shards. When it was dry it felt like placing my hands in puffed rice.
The best description I can think of is like heavy Perlite

After soaking for approximately 20 hours about 2/3 sank and the other 1/3 remained floating.  It was easy to separate the sinkers from the floaters.
After two days 95% had sunk and eventually all of it sank.
I would suggest rinsing well as the water was a bit cloudy.

When I rinsed it, the first water changed from pH from 8 to 6.6, but after several rinses the pH did not change.  
The cost was $28 per 1/2 yard.

I would assume that it is available at many garden nursery suppliers so availability is less of a problem than expanded shale, and yet the price is well below clay medias.

Overall I think it would be a very good media for ebb and flow if some protection were put in place to screen the very small particles.
The material could be separated according to size with a screen, but it packs well enough that it does not fall through the cracks of a net pot like the clay balls, and yet continues to drain well allowing for plenty of air.


Im very impressed by it, and look forward to replacing all of my other medias including Hydroton.  Considering the price it is well worth taking a look at.

  

The pumice worked in a net pot.  Fewer grains fell through the pot than if I had used Hydroton.

 

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Gardening with aquaponics is a passion for me.  For almost 2 years Ive visited my fish first thing in the morning, and its the last thing I do before bed.  I enjoy the science and systems that sustain this marvelous symbiotic garden with biological interactions that continue to flourish and amaze me.

Ill warn you that a lot of what you will find on the internet is hype and rubbish.  For example growing lettuce at four times the normal yield is just not going to happen. Aquaponics is not going to feed the world, and its not as easy as many make it look, and unless you are a top notch salesman you will not grow rich selling produce, and fish or aquaponic systems. Beware of people selling anything related to aquaponics. There are no secrets in aquaponics.

Why do you want to grow with aquaponics?  Chances are you either want to
1. save money on food,
2. avoid kneeling,
3. reduce your water consumption,
4. be sure you are eating healthy organic food,
5. help reduce the depletion of fossil fuel and lower the carbon foot print of your existence.

Maybe its all of these, but "traditional aquaponics" is not a sustainable method. To be fair, I cant think of any method of farming that provides animal protein in a sustainable fashion, especially if we are not able to allow the animal to free roam and forage for their own food. After you add up all the energy involved with aquaponics it still uses more energy to pump water than the caloric energy it grows. But aquaponics is a move in the right direction, and it does save transportation energy. In ideal locations aquaponics could produce 30,000 lbs of fish per acre per year compared to less than 100 lbs for cattle, but dont forget the fossil fuel required to make that happen. For more on that [CLICK HERE].

As a side note, farming in general tends to be wasteful.  400 gallons of oil is used annually to feed  EACH modern human.  34% for manufacture of inorganic fertilizer.  19% for operation of field machinery. 16% for transportation long distance.  By growing in our back yards with free nutrient rich sources which I will tell you about later.  We can save a lot of oil, but we need to be conscious of our own waste.  Pumps, heaters and lights use energy.


This is why I strive to design low energy systems, and grow with the seasons. These integrated systems qualify as Permaculture, and I will show you how to accomplish every one of the goal on that list! My first rule is dont fight Mother Nature. She can be generous if you work with her.

Traditional aquaponics may never grow enough food to get back what you invest, but you will save a lot of water, know first hand how safe your food is, and if you design it with raised beds or vertical towers you will not have to get down on your knees.

Growing a garden is a challenge, at least it was to me. Aquaponics is not any easier, and often times more difficult than soil based gardening. I dont consider myself an expert, just experienced. I hope I can help you get you off to a good start because it can provide a great deal of enjoyment.

Here is a list of topics I will cover

Sustainability
Water Quality
Carbonates, pH, water chemistry and nutrients
Iron
Media beds
Media
Radial Filters
Cycling & Nitrification
The System Build
    Concrete
    Wood Tanks
    International Bulk Containers (IBC)
    Drums
    Bell Siphons
    Timed Fill and Drain
    Old School Fill & Drain
    Air Pumps
    Airlift Pumps
    Electric Pumps
CHOP 1 vs CHOP 2
Level Systems
Flow Rate


Fish
    Compassionate Killing of Fish
     Fish Food
    Breeding Fish
Level Systems
Media Beds
    Wicking beds
    Earthan Beds
Wicking Pots
Deep Water Culture (DWC)
NFT (Nutrient Film Technech)
Vertical Towers 
Bioponics
Plants
Green Houses
    Rocket Mass Stoves
    Evaporative Coolers
    Floors
    Pipe sizes
    Insulation
    Lights
    Heating
Starting from Seeds
Keep a Log
Sea Salt
Pest Control
Site & Experts to follow

I want to talk about the many questions I had as a newbie aquapon, and discuss some brilliant ways to improve traditional aquaponics.

Questions will always come up when designing your first system. I will attempt to remember what mine were, and anticipate what yours are too. I also want to mention an alternative to aquaponics with fish. Bioponics is aquaponics without fish. It uses other sources of nitrogen there by avoiding many problems and expenses involved with raising fish. If you do not eat a lot of fish I encourage you to go this route.

Water Quality
There are often concerns about detritus in the media and water. Let me first say, worms in all of your media beds are very beneficial whether it be Earthan, Wicking, or LECA (Lightweight Expanded Clay Aggregate). They consume dead roots, uneaten food, and with the help of bacteria in their guts, make minerals available to the plants through a process called chelation. They help keep the media clear of excess gunk, and feed the plants in the process. Worms (Eisenia Foetida – the Red Wiggler, Californian red worm) to be exact should be in your system. You can even feed them to your fish.

Carbonates are bad for beginning systems because they remove a level of control for beginning systems (i.e. before your nitrification efficiency is up). Your related acidification is really weak and carbonates can overwhelm the process, leading to chronically high pH. (i.e. 8+) which limits nutrient availability and makes it difficult to stabilize your system where it should be (below 7 for commercial systems). - Nate Storey (Bright Agrotech)

pH and water chemistry and nutrients:
If the pH gets too high you will need to lower with acid.  Buffing from the carbonates in your grow media, and local water supply may make the pH difficult to adjust.

http://www.chemguide.co.uk/physical/acidbaseeqia/phcurves.html

At the point at where the buffer is overcome any further amount of acid will cause a drastic pH change

GO SLOW.  As you add Hydrochloric acid the pH will drop, and then bounce back.  Dont get frustrated and dump extra in.  You will reach a point where it kicks in and then a little goes a long way. It is possible to kill your nitrifying bacteria if you go too low.
Ive never had a problem with low pH, but the same applies.  Add a threshold level of HCl (Hydrochloric Acid) or KOH (Potassium Hydroxide) and then test pH a day later and adjust with a smaller adjustment dose.  This is actually safer than calculating because it allows other variables to impact pH over the course of 24 hrs.

Some people like to keep pH adjusted water on hand.  Rain water can also be used to avoid adding calcium bicarbonate when topping off the system. 

A Reverse Osmosis (RO) system removes calcium bicarbonate from the water.  They are expensive but they eliminate the constant struggle many find when striving to maintain a perfect pH. 

Iron is almost always lacking in aquaponic systems.  The form of iron is very important. The three common chelated forms (iron-EDDHA, DTPA and EDTA) differ in their ability to keep iron soluble and available to plants as the pH increases. Between a pH of 4.0 to 5.5, any form of iron will work (including iron sulfate) at supplying iron to the plant. However, as the pH increases above 7.0, only the iron from Fe-EDDHA will have high solubility. Iron-EDDHA 4 >< 9 Iron-DTPA 4 >< 6.5 Iron-EDTA 4 >< 5.5 Research has shown that the ranking of iron forms from most effective to least effective at supplying iron at high media pH is Fe-EDDHA Iron-DTPA > Iron-EDTA > Iron sulfate. If iron is applied in a form that is not soluble because of high media pH, then most of the nutrient will not be available to plants until media pH is lowered.
In general the best products will say EDDHA (Sequestrene 138) because they work over the widest range of pH. Sequestrene 330 is ETPA and it is more affordable. Use Sequestrene 138 only if your media is alkaline and calcareous If your soil/media is very acidic I would still use ETPA Sequestrene 330 rather than EDTA. ETPA (Sequestrene 330) is the best all around iron to buy if your are maintaining your system between 6.2 and 6.5. Iron Sulfate can be used as a foliar application in aquaponics, and may not be terribly detrimental to your fish, but I would not use it when there are better choices.
Sequestrene is what I use and its widely available on the internet, but others are good too. Sequestrene 138 may has been reported to turn the water red but Ive only used 330 so I dont know for sure if that is true or how much of a problem it is.

Media beds clean, and filter the water, but that is not their primary purpose.  In fact even a bio-ponic system (aquaponic system without fish)  will accumulate muck in the media.  To a certain extent that is what you want for good nitrification and as your system matures it will continue to improve.  What you dont want is food and poo clogging the media, and creating anaerobic spots.  Therefore we remove the detritus from the water with a radial filter.  The main purpose of media is to provide nitrification, and as luck would have it, media beds provide a place to grow plants.  People from the aquaculture world often miss this last point and try to incorporate a very efficient Fluidized Biological Filters as well. 

The primary focus of aquaponics is plant growth and fluidized filters also known as moving bed filters create no space for plants, but there are situations where they may be useful.  For example you may wish to have more fish and have no room for more garden beds.

Media provides filtration, a place for plants and most importantly nitrification.


BSA (Biological Surface Area) depends upon the SSA (Specific Surface Area) of the media.  The higher the BSA the better because the bacteria which provides nitrification likes to grow on surfaces.  Most IBC systems average about 25 ft² surface area per pound of fish.  100 or more sq ft per pound would be really great for the fish, but somewhere in this range is good.

The surface area of the media where the bacteria grow increases with porous media.  Kaldness is used in aquariums because it has been designed to provide a very high SSA of about  244 ft²/ft³, while providing good flow.  Flow is the crux, because even though media such as sand has a high SSA of about 270 ft²/ft³. and a void ratio of about 40% the flow rate is too slow.

There is a wide range of media with good flow and high SSA,  but some to stay away from are any rock that will change the pH such as marble or lime stone and GrowStones in apquaponic systems because they are made of glass which will leach into the fish tank and harm your fish.  They would be great in a bioponic system though.

The best products are LECA (Lightweight Expanded Clay Aggregate),  Expanded Shale or Bio-Char if you are able to afford, and obtain them.  For the rest of us Lava Rock is my preference because it is cheap, porous, not too heavy and contain a lot of minerals for the plants. Microporous solids called zeolites form in volcanic rocks.  According to Russel Water Gardens - Lava Rock has an SSA of 86 ft²/ft³ and a bed porosity of 20%

For comparison I found this reference
gravel (40–70 mm,speci?c surface area of 700 m 2  /  m 3 and bed porosity of 0.4)and a LECA with the commercial name of Filtralite NR(4–8 mm, speci?c surface area of 1250 m 2  /  m 3 and bedporosity of 0.45).
I converted that to inches and feet.
1.5-2.5 inch gravel has an SSA of 213 ft²/ft³ and bed porosity of 40%
1/8–3/8 inch LECA has an SSA of 318 ft²/ft³ and bed porosity of 45%).

Some of these figures do not seem to jive...  It may be that the 2 gravel was not ordinary drain rock.

Nate Storie showing specifications for Sand, Pea Gravel, 3/4" Rock, 1" River Rock and his Zip Tower Media

http://youtu.be/EKGiXoJMLbo

Radial Filters are inexpensive to build, extremely efficient, and offer the side benefit of capturing fry before they are eaten. To grow healthy plants we must keep the roots clean, and the radial filter will do a better job. There are many versions of radial filters on the internet, but the principal is pretty basic, and easy to understand. A radial filter will remove most of the detritus by slowing the water down, and allowing it to settle to the bottom of the radial filter, thus keeping your DWC raft beds, and media beds as clean as they need to be.

Basic radial filter

There have been quite a few other types of filters tested, but any attempt to use filter pads will create a lot of extra work, and jeopardize the clear flow of water if you forget to clean it. Depending on the size of your filter you will be married to that chore more often than you like.

I only do this when my fish have babies, but occasionally I will place a filter inside my radial filter on the exit pipe in order to save the fry that get sucked in. I can then move them to a safe tank until they grow a bit larger.

Cycling
One of the biggest blunders newbies make is to buy fish before the system is cycled.  Cycling involves growing bacterial (nitrification) which will naturally find their way into a aquaponic system.  There is no need to buy this bacteria, and every product I have ever used did absolutely nothing.  This includes products claiming to have several bacteria strains, and those claiming to have special enzymes.  Nitrification takes a minimum of three weeks, and as your system ages this process will mature and get even better.
There is only one way to speed the process.  You can obtain a fresh bucket of media from an established system and add it to yours.  Water from an established system will not work.  To feed and grow the nitrifying  bacteria simply add enough urine to maintain the ammonia at about 0.5 - 1.00 ppm more or less, and let the water flow through the media and it will begin to grow.
There is possibly one other way to quickly establish nitrification, but I have never tried this.

Nitrifying bacteria live on surfaces therefore a high  BSA is good.  Nitrification is a process where bacteria convert ammonia to nitrite and other bacteria convert nitrite to nitrate.  This is a two-step oxidation process of ammonium (NH₄⁺ or ammonia NH₃) to nitrite (NO₂^-) then to nitrate (NO₃^-) .  During the cycling process do not adjust your pH unless it falls below pH 7.  The bacteria prefer a higher pH.  The pH can be adjusted later when the bacteria have become established.  It is this nitrification process that removes the ammonia and nitrites from the water and creates a clean healthy environment for your fish.  Without it you will be doing several water changes per day of burying dead fish.

Nitrogen is a key component of aquaponics.

The United States uses about 13 Million Tons of nitrogen fertilizer a year.  It takes  liters of fossil fuel to make just  2.2 lbs or 1 Kg of nitrogen, so alternative sources is a big deal and I hope I can convince you to use sources of nitrogen such as urine and weeds which are simply going to waste.

We add protein in the form of fish food and that breaks down into nitrogen for our plants.  For most of us this is all we need to know, but if you wish to crunch numbers and maximize the use of nitrogen then I suggest Commercial System Design – Nitrogen Budget. Paul Van der Wolf explains the entire cycle in depth. 


The System Build

Your first system will probably be done as inexpensively as possible, and you may be temped to try some of your own ideas. I can tell you from experience that your tanks need to be sturdy, thin enough to accept a Uniseal or bulkhead, and of a material that will not rot from constant exposure to water which I guarantee you will spill plenty.

Concrete may seem like a good choice, but only if it is sealed. The problem with concrete is that it will affect the pH and if you continually force the pH down to an acceptable level the concrete will also weaken and crumble. There are ways to seal it with pool paint or wax, but its is probably better the just avoid it.

Wood Tanks will rot if water accidentally gets under the liner. I have successfully [built wood tanks using fiberglass], but in the end this was more expensive than a good solid agriculture stock tank which can generally be picked up for about $1/gallon.  Over time the bulkheads tended to loosen - probably due to the contraction and expansion of the wood.

.  

These bunk feeders make good DWC Raft beds and the stock tanks are perfect for fish tanks

The advantage to building your own tanks is you get to make them exactly the size and shape you wish.

International Bulk Containers (IBC) and plastic drums also make very good tanks, and the size is appropriate to most backyard systems. But I like a fish tank that I can reach my hand to the bottom of so you may want to cut your container down just a little.

Drums are often free, so it is an ideal way to start. Some people like them well enough to stay with them. I like the way Justin has built his grow bed using 1/2 drums because there is no frame below the drums, but I would have added a support leg in the center or used 2x12. By the way a barrel has a removable lid a drum has two bungs.

Bell Siphons work while the flow remains within the parameters they were designed for, and as soon as something changes they will fail. As much as I enjoy listening to a bell siphon cycle through its phases; and even though Im the guy who came up with the idea to use a small reservoir at the end of a breather tube, I will never use another bell siphon on any system I build. The reservoir helps, but its a Band-aid fix. Why bother with a bell siphon when there are better solutions.

Timed Fill and Drain are a better choice and they conserve energy. Running a 100W pump 24/7 uses 2.4KW per day 365 days a year. A 15 minutes on 4 hours off cycle consumes 16 times less power than a continuous run bell siphon system! I do not believe turning a pump on and off shortens the life of a pump, but everyone can have an opinion.

Media beds traditionally use a Bell Siphon, but a Timed Fill and Drain system will use less energy and run with far fewer problems.

Timed Fill and Drain systems use a small weep hole which allows the media beds to drain more slowly than they are filled. A stand pipe allows any excess water to overflow back into the sump tank until a timer turns the pump off. The beds are filled several times a day, and when the pump shuts off, the water weeps out and drains the media bed.

Old School Fill & Drain

I dont know if this siphon valve has a name or how well it works, but I first saw it in Travis Hugheys Barrel-Ponic Manual. It works by pulling a toilet flapper with the weight of a 2 litter bottle. Just giving you all the options.

Air Pumps
Im running my air pump to 9 air stones and moving over 1000 gpm with 2 airlifts. Im using all the air (200 lpm) my Eco Plus 7 compressor can deliver. It runs at 93W wide open and 51W when closed.
The specs say an Eco Plus 7 compressor is rated at 200 lpm 5.1 psi and 280W. I believe the 280W rating refers to the maximum heat dissipation the motor coils can endure. Ive rebuilt Active Aqua air pumps and Ive looked inside this Eco Plus 7 and found the Active Aqua to have less space within the enclosure. After I could no longer rebuild my Active Aqua I bought the Eco Plus. My feeling is that Eco Plus has created a larger cooling area that allows the pump to operate much cooler and last longer. I could not pick my Active Aqua 70 lpm up with bare hands whereas the Eco Plus 200 lpm is only warm.

 

Ive done a similar test with my Ametek Rotron EG DR083 regenerative blower and found that restricting the outflow increases the Wattage, contrary to the compressor. The regenerative blower is great for air stones where the depth is usually pretty shallow. It delivers 521 liters per minute and uses just 118W, but the compressors advantage is the ability to deliver 5.1 psi. The regenerative blower has only 0.867 psi. So the regenerative blower does not work well for airlift pumps but it blows a hell of a lot of air to air stones!

Airlift Pumps 

Air stones are highly recommended throughout any system and since we are running an air pump why not utilize it for pumping water too? Thats right airlift pumps will move large quantities of water on less power, and aerate the water while doing so.

One of the really nice things about airlift pumps is the way they can pass solids without clogging. They are in my opinion far more reliable than centrifugal pumps, and a whole lot less expensive. My airlift can be built for less then $10 and it delivers over 1000gph.

Electric Pumps - If you purchase an electric pump there are some considerations. To keep this paper short (lol) Ill insert a [Link Here]

CHOP 1 vs CHOP 2
CHOP (Constant Height One Pump) Traditional Aquaponics uses either a CHOP 1 or a CHOP 2 design. The water level in the fish tank is always a constant height and one pump delivers water to the fish tank which overflows into the media beds and then back to the sump tank. Chop 2 differs by one pump delivering water to both the fish tank and the media beds. These each return water back to the sump tank. The advantage of CHOP 1 is greater flow through the fish tank. The advantage of CHOP 2 is the ability to isolate the media beds and the fish tank. These traditional systems aerate the water by drawing air down through the media each time the water level fills and drains.

Level Systems
There seems to be some misconception that fill and drain action is required for good aeration.  This is simply not true.  There are several methods to aerate water.   

Air stones, with an air pump are generally used in any type of aquaponic system  I highly recommend many air stones throughout the system, and air lift pumps definitely ensure good aeration.

Level systems do not waste energy lifting water from a sump tank.  Instead the water is simply pushed along through the system, remaining the same height from one section to the next.  The air lift pump, and air stones provide all the aeration necessary for good healthy roots.

This of course does leave the roots sitting in water in the media beds, but so do raft systems.  There may be a few plants that dont appreciate constantly wet roots, but most do fine.   Media beds have been included in every successful aquaponics system since day one,  but a new concept has evolved which integrates wicking beds with aquaponics.  Its called Earthan Beds, and Ill tell you more about that later.

Flow Rate - Kieth Tatjana recommends twice per hour, but no more. The Aquaponic Gardening Community site recommends once per hour. So if you have a 100 gallon fish tank you should pump 100 to 200 gallons per hour. These rules of thumb are good enough, but if you are designing a commercial system then I would refer you to "Why Flow Rates are Critical in Aquaculture" written by Paul Van der Werf.


Fish are such a wide topic. My advice is grow what you like to eat, or grow what you like to look at, but dont grow what does not belong in your neck of the woods.
Tilapia in Maine is going to require heating the system, and take it from someone who has been there, it gets expensive. Catfish, are a good all around fish, but even though they can survive, they will stop growing during the cold days of winter. If you live in Florida or Hawaii you might like to grow tilapia, but even in Florida the winter will require some heat.
The nice thing about Tilapia is they grow pretty quick, they are hardy, and they reproduce well, but catfish kept in a warm water tank will also fulfill these qualities. If you live in a very warm climate, go for it. But most of us will be better off with a local fish that is acclimated to our area. Perch, Blue Gil and even trout are being raised in cool climates.

Larger systems are more stable, but start small. A 100 gallon tank with about 16 lbs of fish and 16 sq ft of garden is a very nice system. You can expand the grow bed on that system a little, and stock the fish a little heavier, but for starters its best to keep a light fish load.

Breeding Fish - I have found that fish will breed without my intervention. But some like to identify the males and females and place one male among several females. Sexing fish is not easy, but Robb Nash has a good method in his link. Once the fry are available it is a good idea to separate them so they will not be eaten.

Compassionate Killing of Fish

Inhumane and totally unacceptable slaughter methods, that can take a long time for
fish to lose consciousness and die, should be prohibited urgently. These include
suffocating fish in

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Duckweed and String Algae

The video above is one of the best for both duckweed and string algae.

String Algae may begin to grow in your system.  Its not all bad because it can be useful as a fish food, but it tends to clog the system.  If your fish dont keep it under control a small amount of salt in the water will kill the string algae.

There are many varieties of duckweed.  I have two, but one or the other will tend to prevail depending on the time of year.  Duckweed can be rinsed and used in salads and it provides good protein for your fish.    Under ideal conditions duckweed will double its volume in just a few days, but you will probably have to raise your duckweed separate from your fish because they will eat it faster than it reproduces.

Duckweed cleans the water, but it can also exclude oxygen if it grows too thick.  It prefers warm water, and seems to grow out of control when the conditions are right.  Creating the right conditions can be difficult, so I spread it around various areas and let it grow where it wants to grow. 


Good article about Duck Weed
http://www.fao.org/Ag/AGAInfo/resources/documents/DW/Dw2.htm

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Ive been inspected

Virginia Department of Game and Inland Fisheries
His name is John Odenkirk, and hes Certified Fisheries Scientist #2043. Hes the guy who inspects aquaponics facilities for the neighboring 11 counties - required for facilities that are requesting permission to raise tilapia.

He came. He snapped. He left.

It was a pretty painless process. And after he conveys the form and picture to the right people, my permit should be in the mail in a matter of a couple of weeks.

I was happy to show him my auto-siphon. Didnt look like hed seen one of those before. And I was happy to show him my current water chemistry: 7.6 pH, 0.0 ppm Ammonia, 0.0 ppm Nitrite, and 80.0 ppm Nitrate.

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Starting From Seeds

Ive had a lot of trouble with my seed starts.  But today I read a forum discussion that made some very good points which I will begin to follow.  The following is a list of dos and donts.

Starting from seed requires moist, but not wet conditions.  Starting your seeds in the Deep Water Culture (DWC) may keep your small seedling too wet.  It would be better to water as needed; maybe two or three times per day depending on the heat and humidity.  Green House humidity may keep the seedlings too moist.  Using a fan to move air over the seedlings can be helpful, but you may also need to open the enclosure and let dry air in to bring the humidity down.

My seeds do well when started outside in open air, but Id like to be able to start seeds in the cold Winter months too.  Im thinking I will get a small heating pad and start my seeds in the garage.  The humidity will be lower so Pythium will be less likely to affect the small seedlings.  Once they harden off I will be able to move them into the garden room.


Starting seeds directly in the net pot, or media that the plant will live its life in saves a lot of time.  Let me directly quote  Vlad Jovanovic 

           Link to Comment

"All the stuff you see in my rafts were germinated directly in net pots filled with hydroton. I just dont put them in the DWC trough until about 10-15 days after they germinate, but they all seeds start off directly in hydroton. This has a number of advantages.
1). There is no transplant shock for the seedlings Since the seed is started in the same place it will live out its life, so no waiting days and days for them to get over transplant shock and start growing again. So better for them.
2) Its a HUGE time and energy saver. Transplanting seedlings sucks IMO and is a totally un-necessary waste of your time/labor in most AP scenarios. So better for you.
3) Its also cheaper that way, since there is no coco-coir, vermiculite, perlite etc...to buy.
4) No soil born pests or pathogens (even in bagged and bought products Ive often come across various larva and who knows what else that you cant see...fungal/bacterial).
Starting seeds off in soil, or any other medium, seems pointlessly time consuming, counterproductive, more expensive, and doesnt give germination results that are any better than starting them off in a LECA media, and can be the source of many a pathogenic headache."

Old seeds dont germinate. 
Get your seeds fresh from a reputable source.  Your local hardware store or grocer may not turn over enough stock to ensure that  the seeds are new.

Begin with a sterile media.   Here is a tip from Jon Parr

 Link to Comment

 I would personally mist the plants and surrounding area lightly with hydrogen peroxide to kill spores while handling, and to help prevent any spores from going airborne. No big deal, but H2O2 is a relatively safe disinfectant, and leaves nothing behind but water and oxygen.

I have tried this and ran into problems when my H2O2 solution was too strong.   A 3% solution is a common topical strength found at drug stores and would not need to be diluted.

After many of my seedling failed due to Damping Off and more specifically Pythium – a genus of parasitic oomycete I have taken to is boiling the media I plant in.  Starting with a sterile media, and avoiding contaminates from sources such your dirt garden will help to ward off these parasites. Nursery transplants are generally pretty sterile, but since you dont really know it does not hurt to be cautious.  

Jon also offered this tip!
Link to Conversation

Indeed, be careful about using H2O2 or any dissinfectant in AP, of course. But in order to harm your bio filter, it must reach your biofilter as active H2O2. If you dump a whole bottle of hardware store 3% in your grow bed, the H2O2 will kill single celled organisms indiscriminately as it disperses through the system, leaving in its wake a sterile pathway. Big deal. If it doesnt wipe out the whole system, the system will recover, probably without hiccup. That cant be said of any other disinfectant. The truth is that H2O2 is very short lived in an abundance of bacteria, as the bacteria it kills robs the extra O, and leaves behind H2O. Of course you can do damage, but it is a very mild risk for the benefit it carries. If your media is dry for 2" like its supposed to be, then you can fog the plants and surface liberally (use your noggin), and the H2O2 wont make it to the fish or the biofilter. I do it all the time.
The fact is that spore carry the problem to other areas, and stick around to cause problems again, and H2O2 kills spore. It doesnt kill the fungus, it doesnt kill the plants, it doesnt kill insects, but it does kill spore and bacteria. If you really want to impress your friends, use a cap-full of H2O2 for the first watering after you plant seeds. It will kill any spore and bacteria immediately surrounding the seed, and rapidly quicken the softening of the hull, cut germination times in half, and increase germination rate. It may even fix your infected seeds, IDK. 
Yes Bob, 1 1/2 to 3% can be put straight in a spray bottle, and is a good disinfectant to use for your garden tools, cleaning pumps and hoses, test equipment, fish nets, etc.
Dont let any go straight to the fish tank, as there are far fewer bacteria to sacrifice before it hits the fishs gills, which could be lethal.

In Summary:
 Keep it dry
  Water only as needed
 Keep it sterile 
  Spray with Hydrogen Peroxide
  Boil the media
 Use fresh seeds
  

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What lurks beneath

A Monster Zucchini
I popped out to the garden tonight to feed the fish and spent a few seconds gathering ripe eggplant and tomatoes. As I passed the end of the garden, I caught a glimpse of "not-leaf" suspended from the edge, hidden by a curtain of leaves.

Oh. My. Goodness.

My daughter pointed out that August is host to Sneak Some Zucchini Onto Your Neighbors Porch Day. To quote from the Holiday Insights page:

Experienced gardeners know that Zucchini is one of the most prolific plants in all of the gardening world...

By the time August arrives, gardeners are reaping far more zucchini than they can possibly use. Zucchini growers become desperate, as they try to give zucchini away to family, friends and everyone they encounter. By August, even non-gardeners have had enough. Everyone avoids you...

Desperate times calls for desperate measure. Its time to sneak over, under the cover of darkness, to your neighbors porch, and unload some zucchini.

Someone wondered why this "Zucchini... Day" is held on August 8. Think of 8/8, which is like infinity over infinity, capsized.

Luckily, I only had a couple of zucchini plants, so the harvest has been just right for us.

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Yellow Mottling on my Spinach Plants

Update 2012/12/23
In this post I examined and searched for the cause of yellow mottling on these spinach leaves.   Finally I found that the cause was an Iron deficiency.  In the months that followed I posted several more articles with good information about this and other nutrient related signs, problems, and solutions.

For a scientific explanation of the chemistry behind the bio availability of Iron go to
[Are These Rocks Nutrient Theives?]
and
 [Assimilation of Nutrients]

For a detailed yet condensed collection of charts and facts go to Nutrient Deficiencies

Below is a record of my wondering search while I learned what I needed to know. I would prefer to simply delete it, but you may relateto my learning curve and find something interesting along the way.





Update 2012/06/07
Im still having problems with yellow leaves.   I have brought my PH down from 8.2 to 6.6 and I have no salt in the system   I have also added 1/2 a bottle of Microbe Lift Chelated Iron. Ill Send an update in a few days with the results.   I have more iron on order as well as a GH/KH test kit.   Hopefully I will get this figured out.

Update 2012/04/14
"A plant injured by excessive sodium first displays mottled leaves or yellowed tissue between the veins of leaves. This is followed by leaves that are dead at their tips, at their margins, and in areas between their veins."  - WateReuse Foundation

My search for the cause continues. I had not seen any insects so I hung sticky cards to trap them.  All I got was two mosquitoes.  Several weeks ago I pushed my salt levels up to 0.35% because I had a few fish that were damaged during the transfer to the aquaponic tank.

Ive been bringing the salt level down slowly and it is now at 0.20%.  In the past when I bumped salt levels up in my pond I did not notice any damage to my ornamental plants, but Spinach and Tomatoes may have a lower tolerance.

I will begin to lower the salt level over the course of the next week and see if the new sprouts show any of the same signs.

Further information:
http://salinitymanagement.org/Salinity%20Management%20Guide/index.html


Update 2012/04/12
After receiving assistance from Zalinda Farms Inc. , I now believe the problem may be caused by Thrip.
If not this information is still a value.  Keeping a vigilant eye on the crop is always important and Thrip is just one of condition to look for.

I have yet to actually see the Thrip, so I will purchase some Sticky Cards.  If I find Thrip I will use  Monterey Garden Spray to control the pests.  The literature indicates that it is a safe bacteria. 

Natures Control also offers several solutions.  One is Predator Nematodes

but in an aquaponic system this may not be an option.  The instructions state "The important things are to use them within 2 hours of mixing, because after that they start to drown".  ... " Theyll live longest when the soil stays moist, but not saturated with water."
I suspect they might be washed away into the water each time the grow bed ebbed and flowed.

Another solution is this Pirate Bug shown above.  They too are susceptible to environmental conditions.
"Thrips Predator Mites (Amblyseius cucumeris) are most effective under conditions of 70-85% humidity, against all species of Thrips. They will also eat an occasional Spider Mite, and other small pests. However, reports have been poor in low humidity environments, so use these predators in greenhouse and other interior locations with high humidity levels only. "

Two types of sticky Traps are also offered by Natures Control.  They say "Customers report success using Sticky Blue Traps against Thrips & Leafminers. Especially recommended for use on roses."

I found further information at 
http://biocontrol.ucr.edu/wft.html
The definitions of INSV and TSWV are as follows:
Vectoring of plant diseases. Western flower thrips is a vector of many plant diseases, the most important of which for greenhouse producers are two plant viruses in the genus Tospovirus: impatiens necrotic spot virus (INSV) and tomato spotted wilt virus (TSWV)
 
 





Original Post
I wonder if anyone can help me diagnose this problem Im having with my spinach.
I suspect either a lack of light, salt burn from treating my fish, or a bug, but I see no bugs.
My spinach leaves are mottled with yellow. 

The orange arrow points to a very small white area that I found behind the stem of a leaf I removed.  It looks like foam.

The underside of this leaf has very small round white spots.  This picture is through a magnify glass.

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