Backyard Aquaponics
A place to discuss aquaponics

thanks guys , keep it up , some very good advice and soon i think we will get a good combination of ideas as to what is the best overall , i like both Tc and Rupes approach to this area.... first step is i will get a water analysis done on the source ..do i just ask for a broad range test of ph and minerals ?

Well I'm not sure what sort of labs are available there, but the testing I got done on my source water as well as on some of my system water was what one might get for agricultural irrigation water. It looks for many nutrients and minerals as well as noting pH, EC and salt levels since those things can impact irrigation systems, soil structure, and plant growth as well as how to fertilize or fertigate.

Then I got a recommendation for hydroponic nutrient levels (for lettuce in this case) so that I could roughly compare what I had with what was recommended for hydroponics and then paying attention to the plants, see where I most likely needed to make adjustments. Each test cost about $30 USD plus another $10 to test for nitrogen. Not the kind of testing you are going to want to pay for weekly or anything but if farming for a living, it would probably pay to get some pro lab testing done a couple times a year or when problems arise.

And Guys, try not to let Rupe rub you the wrong way. I see him sometimes get really nit picky about semantics even to the point of seeming to be a troll but if you can get him to get into the details on the chemistry, he can teach a lot.
I must thank Rupe for stepping in to help explain chemistry since about all I'm capable of doing to watering it down into lay terms.

Now I am interested to hear his take on the testing/supplementation as it would pertain to small farm to commercial operation. I listen carefully to guys like Vlad, Jesse Hull, Nate, Ryan, and Rupert when it comes to plant husbandry, supplementation, chemistry and the like. I'm just the technician that is good at making water flow around where I want it/how I want it and When I want it.

There is a difference between hydroponics and aquaponics, and it is basic to the field. In HP there is an attempt to provide all the nutrients the plants need, by adding in specific chemicals and nutrients. In AP there is an attempt to provide all the nutrients by letting natural cycles do the work.

In HP, my understanding is, if you neglect specific nutrients the plants don't grow, die or do not achieve the result. In AP, they achieve the result almost always, and when they don't the symptoms tell you what is missing. (they do also in HP, but the chemical mix is less simple than simply adding in iron chelate or a bit of potassium etc.

I've never done HP but I have browsed some of their sites while reading up on things connected with AP. Almost no HP people can produce without careful monitoring of the nutrient mix; very few AP'ers get to a stage where they actually have to be so concerned.

Plus, we get to eat fish!

I often look at the difference between HP and AP like the difference between Chemical soil agriculture and more natural or organic or permaculture soil growing.

In chemical agriculture, the soil is largely already depleted and they are trying to make the crop grow as fast/big and good looking as possible while keeping costs as low as possible. It is all about marketability and people don't get to taste the crop before buying and looks are far more important than actual nutrition.

In the more natural or organic forms, the farmer is actually most involved with soil health, feeding and promoting all the good soil microbes and by making sure the soil is very healthy, reducing the need to use the chemicals to make it all work.

In aquaponics we have the microbes! and even some of the macro soil life if doing media aquaponics. We have to take things at a somewhat slower pace since what we do to our systems affects our primary partners, the bacteria and other microbes living in our systems and making nutrients available to our plants. In aquaponics we have to be very careful of anything that can be toxic to not only us, but also fish and even more importantly the microbes making our systems run. Many of even the "organic" pest controls are not safe for fish and if a plant or fish disease decimates a system, it is a hard decision about do you clean everything out, sterilize it all and start ALL OVER? Or do you wait and try to promote good bacteria to out compete the bad? Or are there other things that would work without danger?

Anyway, I've done a very small amount of home scale hydroponics and a lot more of the Aquaponics. I find the aquaponics with it's larger mass of water and additional output of fish as well as the "growing more food with every drop of water" angle to be more suited to my nature. I always hated to dump and replace my nutrient solution in hydroponics, it seemed so wasteful of water and runoff pollution in Florida is a big deal here, I wouldn't want to contribute. Aquaponics can definitely be much trickier when it comes to lager scale and trying to get pretty product to market and trying to compete with cheap produce from big ag makes it necessary to find a niche market and people who want our Toxin free produce from aquaponics (remember we can't cheat because we have fish in the system that would be killed by spraying the extreme stuff even if we didn't it secretly.)

I was of the understanding that more complex fungi and bacteria on the root mass cue chelation and other processes needed for nutrient uptake that are more complex than just the nitrification cycle.

We now see that a forest can share micronutrients via mycelium for kilometres, to assume aquaponics is merely chemistry is narrow minded and flawed.

Oh Aquaponics most definitely has far more than JUST the nitrification cycle bacteria going on.
I've had beds with mycelium as well as plenty of other bacteria and microbes as well as worms and other larger critters doing their work for me.

While ignoring the chemistry can get you into trouble so can treating an aquaponics system like a chemistry set.

Good analogy/comparison

If only the organic certification bodies would see AP accurately in the same way

It is only rare situations where I would see any benefit in trying for Organic certification myself. "organic" has gotten all watered down and adulterated anyway by big ag. The only reason I could see to make it worth while for an AP farm to bother with certification is if they are ONLY selling Wholesale to large distributors then to get any premium for their product they would need the word "organic" on it.

If you are anywhere that you will get to talk to the customers and explain how much better than "organic" aquaponics actually is, then why spend all the extra money for certification when it likely won't bring you any more money on the product being sold directly to the end user.

Here in the US it is possible to get Organic certification on Aquaponic Produce but I only see that as helpful to farms that need the "organic" certification in order to sell their produce. (Perhaps there are some Markets in California where customers will only get close enough to venders that have a big "Organic Certified" banner but here in FL I actually make a big point of explaining that NO I'm NOT "certified Organic" what I'm growing can't even use many of the "organic" toxic pesticide sprays and NO way I can cheat and use the chemical pesticides because instead of chemical fertilizers in my tank I have fish.

So, from the discussion... it seems we have no idea what level of nutrients plants need to grow in aquaponics...

No idea what level of nutrients we are providing...

And we're just adopting a "suck it and see" approach....

Sounds like a firm basis for the commercial success of aquaponics... and nutritional value of aquaponics produce to me....

Where do I invest....

No Rupe, I'm not saying we have "NO IDEA". As you noted we do have a place to start looking roughly basing the needs on hydroponic and soil crop plant needs.

BUT I would be willing to bet that further research will eventually show that what nutrient levels are needed to be supplied in aquaponics is somewhat different than the levels that need to be supplied for hydroponics since the form in which we are supplying them in Aquaponics is different.

I do think that many of the aquaponics operations out there are starting out with the suck it and see approach and that is where they often run into problems because many of them don't even know what they are looking at when they do start to "SEE" problems. And there are "training seminars" still being regularly given where they insist they do not supplement anything other than adding the calcium and potassium hydroxide to deal with pH, and Maybe Iron, even when the plant look BAD to the point of unmarketable.

I think the trick (at least for me) is finding out what the really good horticulture guys (Jesse, Vlad, Ryan and Nate) do when they see certain deficiencies and what sort of levels they try to keep for those problem nutrients.

But this is where I fundamentally disagree with you TCL... on both points...

The nutrient requirements for plant growth are known... as are the nutrient requirements for fish growth...

They must be.. for several reasons... and it doesn't matter what the production method is...

Agriculture determines it's fertiliser types, and application rates... in conjunction with soil types, and soil testing... to provide the appropriate fertiliser mix and application to meet the plant nutrient profile... at various stages of plant production... (and allowing for leach/drain rates).. per species..

Likewise.... aquaculture determines the feed type proportions/content.. and feed application rates... in conjunction with source water testing... based on the various stages of growth... per species...

Similarly, the same applies to hydroponics....

All three disciplines can be achieved with reasonable success in a backyard context,,, with minimal knowledge and/or testing...

But commercial production must for reasons of profit,... be able to measure/control/adjust... as required by circumstance... location, season, weather etc... to achieve consistent and predictable growth...

Eyes, ears, touch, smell etc.. learnt experience and even a degree of intuition by the operator are universally applied in all three areas...

But the degree of risk/unknowns are minimised...

Now contrast that with aquaponics.... while the nutrient requirements of the plant/fish remain the same...

And in a backyard setting.. the same "suck it & see" approach can be entirely successful...

When you extend aquaponics into the commercial arena.... for some reason... most people refuse to adopt the same principles, knowledge, practices etc from the other commercial disciplines....

Even though they are common to all the other disciplines... the vast majority DO (as you say).. adopt a "suck it & see" approach... both in terms of system design... and production expectation...

Instead falling back on this idiotic romantic notion that somehow... aquaponics is different... or even "natural"... and/or "balanced"

There's nothing "natural"... or "balanced" about agriculture, aquaculture, hydroponics... OR aquaponics...

Heck nature isn't even "balanced"... but always in a state of flux...

Bear with me... take a look at the following three extracts...

The first two are feed analysis from a fish feed supplier.. the first for juveniles, the second for "mature" fish...





Now compare the above two analysis.. with a standard Hoagland hydroponics nutrient solution composition...



What might be the things you could conclude from the above???

Umm,

one is looking for and finding Nutrients
and one is looking for and finding Minerals?

From left field: would the dissolved nutrients need to referenced to the nutrient content of the product. Fish and Plant.

I'm not really disagreeing with Rupe, I'm just pointing out that there is more to it than just comparing the fish feed and source water with the recommended hydroponic nutrient mixes.

Another variable that needs to be figured into the calculation is what % of the nutrients in the fish food are retained in the fish flesh and what % are the waste that is to become the plant minerals?
(I know there have been some studies done on this and it does seem to vary a bit depending on the feed and the fish species as well as growth stage.)

Add to that the fact that some of those constituents of the fish feed/waste take more time to be mineralized into plant usable form and some of that waste may be getting removed from the system in some methods.

This is definitely not a one size fits all math/chemistry equation of simply adding the source water minerals to the fish feed and then comparing to the hydroponic recommendation and getting the answer of what needs to be added or stripped.

If one wants to fine tune the nutrient makeup of the minerals for the plants, one is going to need to do some extra testing of the system water until all those other variables can be quantified and published for all the different species being cultured and all the different feeds out there as well as the different mineralization or solids removal regimes.

What Rupe says is a starting point but I don't agree that it is the final answer. The original posters question was how to test. I'm curious Rupe, how would you recommend testing for some of the other nutrients beyond the API test kit and Iron? Or are you saying you would just crunch the chemistry equations based on your fish feed and source water and supplement from there?

And my other point about plant usable forms of nutrient and minerals. I'm not saying that plants don't need a certain amount of different things to be taken up to grow or that what the plant needs to absorb in Hydro or AP is any different. What I am saying is that it very well may be possible that you don't need as much of a particular element in the solution in aquaponics for the plants to be able to get enough of it as you might need in the chemically supplied form in hydroponics.

For instance (Hydroponic Lettuce target values)
Nitrate Nitrogen, NO3-N (ppm) 200
Basically saying that in a hydroponic system set up to grow lettuce you want to try to keep your nitrate level at 200 ppm in order to grow the crop.

How many people doing aquaponics and growing lettuce have found that they need to keep their nitrate levels up at 200 ppm to grow a great crop of lettuce?

I don't really expect that the lettuce in either case actually takes up much more nitrate than the other in order to grow, however it seems that in hydroponics one must make sure there is far more available to the plants or perhaps it has more to do with a balance between different things in order for the plants to grow well?

I use the nitrate as an example because it is what almost everyone tests for in Aquaponics and I know I've heard many people insist that their Nitrate readings are very low while they also show pictures of their plants doing very well. Is it that they are lying about the nitrate readings? Or that their plants don't actually need much nitrogen to grow? Or that there is a little more to it than simply the ppm of nitrate in the water and how much nitrate the hydroponic guys insist that you need to supply?

It is kinda like the whole idea of supplementing Iron, if it is in the wrong form, the plants can't take it up. If the plants find it easy to take up what they need, you don't necessarily need to supply as much (as in have the pH in the right range) but still, some forms of iron are more accessible to the plants. Just like some forms of protein are more digestible by the fish and some forms of calcium supplements are more digestible for people. I think that some of the nutrient forms in aquaponics are going to be more usable by the plants and therefore we may find that we don't HAVE to keep our Nitrate levels at 200 ppm (or whatever value the hydro guys recommend for a particular crop) in order to grow very successful crops.