In a fish culture system we have waste in two forms. First we have discharged water. This water in itself already contains a lot of
nutrients and small solid particulate. The other form of waste is solid matter. Either of these two turned loose in a river or lake will cause
a problem. They can be sprayed on a field and they will break down much faster than normal farm animal manure because of the fact
that it is already very wet and there are bacteria working on it when discharged. However, this is still not the final form for plant food. It
still must go through this process.
SOLID WASTE AMMONIA NITRITE NITRATE = PLANT FOOD
After considering how nature works and recognizing the time involved for complete break down of the solid matter we determined that
what we needed to separate the solids long before they got to the aquaponics. We then built a massive clarifier prior to the plant
growing area that would allow for the solids to filter out before they got to the gravel bed. (See S-92 filtration) The effluent would now
pass through the clarifier's, then through the plant beds and then back to the fish system. After operating this system for several
months we did find that we were able to keep the gravel beds from clogging but the down side was, we had to clean the clarifier's every
three or four days. This took a lot of time and effort and now we had another problem, what to do with all of this solid waste. Wasn't the
purpose of all of this to get rid of the fish waste by having the plants eat it?
Within a month we found there were other problems with this new system. While the gravel plant media was staying clean, the
media and the plant roots were a poor bio-filter. We were still getting too much ammonia and nitrites back to the fish tanks and the
plants were being stressed from this as well. We also found another issue that concerns me to this day when people use this method.
We found several bacteria, including e-coli, in the growing beds. What made this such a concern to me was the fact that I did not want
e-coli in my fish tanks and I also recognized that if someone were put their hand in the gravel media before picking a tomato there
would be a good chance the tomato would be contaminated with the bacteria. After a discussion with several knowledgeable folks at
the University of Delaware they stated that this should not be unexpected since this would be prevalent in any septic tank where solid
animal waste was being broken down and the gravel media beds were acting just like a septic tank in that they were capturing enough
solid waste to encourage the present of these bacteria. When we inquired as to how to deal with this we were told that one method
would be to break the solids down with both anaerobic and aerobic digestion, just like they do in a municipal waste water facility,
before the waste was used for plant crops or returned to the system. They were also uneasy with returning the water to the fish system
in the first place. Their analogy was, if you were to somehow treat the waste in your septic tank in a primitive manner and then return it
to be used in your house you would be in jeopardy. Since no animal can do well living in his own waste, why would you expect a fish to
be any different?
Now it was back to the drawing board. We knew two things after all of these trials. We needed to completely remove the fish waste from
the fish system in a positive manner and never bring this back to the fish system once any of it was removed. We needed to clean the
water of all ammonia and nitrites. This was easily done with solids filtration and bio-filtration. We also knew from the trials that the fish
waste made great fertilizer when properly prepared. There was only one solution. It would require two recirculating systems. One for the
fish and the other for the plants. The follow up research would treat each one as its own entity.
Building better fish filtering system has always been the main focus at our research facility, so nothing would change there. Developing
a method to utilize the waste from these fish would be a new focus. Drawing on the science of treating waste in a tertiary, or three stage
process like used in waste water treatment, we designed a small, inexpensive unit that could be build from common materials found in
the construction industry. In our system we call this the digester. All of the waste from the fish system goes here. Once it enters this
point it is never allowed to go back to the fish system, The digester, using aerobic (ambient air) and anaerobic digestion will break the
solids down to a clear liquid nutrient in a matter of days. From here the pure nutrient is circulated to the plant beds and back to the
digester using a flood and drain method.
At Global Aquatics we have incorporated in all of our S-series fish systems devises to totally digest the solids by means of an aerobic
digester vessel and then coupled that to special plants production trays. The nutrients are then delivered to plants by a timered pump.
Unlike Hydro-ponics, our plants are not growing in standing water, but rather in porous media which traps the nutrients around the
SOME INTERESTING FACTS
Global Aquatics developed the first true commercial aquaponics system in 1986 as a part of an experiment in conjunction with the Food
and Economic Department at the University of Delaware. The original scope of the experiment had nothing to do with what we know
today as aquaponics, but rather was an experiment to build a better biological filter to provide pollution free aquaculture discharge. The
experiment started in April of 1984 and over 100 different plants were used to see which ones would work best to remove all of the
nutrients from the water. By the end of 1986 we had discovered a whole new agriculture science. We had developed equipment and
methods that not only consumed the nutrients, we had figured out how to grow vegetable crops that were far superior to normal
hydroponics crops in both texture and taste.
NUTRIENT LOAD IN FOODS
While this may sound a little simplistic, the reason foods grown using organic fertilizers are so superior to those using chemical
fertilizers is because it is just natures way of doing things. If an orange is suppose to be chocked full of vitamin "C" the elements to
cause this to occur have to be found in the food the plant takes in. When someone is using liquid nitrogen, a very good plant
fertilizer, to grow the parent plant, where are the elements needed to add the food benefit of the fruit? The answer is, it is not there.
This is why hydroponic tomatoes have no flavor. In order to get the full nutrient load in any vegetable or fruit you must be able to
provide all of the bases chemicals in the plant food. Nature has given us the way to achieve this by using nature animal waste and plant
compost. Using this method is just a continuation of the natural recycling system.
WHY IS THE FLOOD AND DRAIN SYSTEM SO EFFECTIVE FOR PLANT GROWING?
Before I explain this I need to say, not all plants need to use this method. Some plants like lettuce do very well in aquaponics using the
raft system. In the raft system a pool of water is used. The lettuce seedlings are then inserted into small holes punched in thin foam
boards and the boards are floated on the water. The lettuce plant will send it's roots into the water and get its nutrient from there. For
many stalk plants such as tomatoes and peppers the flood and drain works the best. Here is why.
First lets look at how Mother Nature does things. We all know the benefit of worms. Among the many things they do is they drill holes
on the ground. So why is this a big deal? It is because of the way a plant root system works. First of all, the roots need water. When it
rains what is the best way to get water to the root? Yep! Down the worm hole. The second thing is aeration. While the plant leaves take
in carbon dioxide and expel oxygen, the roots do the opposite. They take in oxygen and put out carbon dioxide. In order for the plant
roots to get oxygen it has to be able to get into the ground. In order for the carbon dioxide to leave the soil it has to have an escape
path. Hence, the worm hole.
When we grow plants in a loose gravel bed we can easily manipulate things to copy nature with the root system. For one thing, we all
know that too much water around the roots will kill the plant. This is for several reasons. One is the root can not breath to expel the CO2
or bring in the O2. The second thing is, with even a little too much water keeping the roots real wet, the CO2 will eventually become an
acid that will cause root rot. This is a problem sometimes with the drip method of feeding plants and a lot of times with those using the
plants as bio filters. The gravel does two main things. First of all it is the media which holds the plant in place. The second thing is it
is a place for moisture to cling to feed the plants. After the plant is set in place, the water to the trough containing the plant and
gravel is turned on and fills the vessel to the top soaking all of the stones. Once this occurs the water is shut off and the water is
allowed to drain out. In the Global Aquatics systems this drained water just returns to the digester to be used again during the next
Once the water has been removed the empty spaces between the stones load up with fresh ambient air. The plant begins to do go
through the life process. The roots are supplying the plant with the nutrient it gathers from the moist stones, they are being supplied
with oxygen from the trapped air and of course they are putting CO2 into the spaces. About 12 hours later the water is once again
turned on. As the water fills the voids in the stone the CO2 is flushed out and a new supply of nutrient coats the rocks. Once again the
water is drained away, new oxygen comes in and the process begins all over again.
THE RATIO BETWEEN PLANTS CROPS AND FISH
I get asked all the time how much produce will you get from one pound of fish. Although this is difficult to measure most people who
have knowledge in this will give you a number of about 15 to 25 pounds of veggies per pound of fish. Of course this will vary depending
on the crop. It is a safe bet that you will get more pounds of tomatoes per pound of fish waste than you will from lettuce crops. This is
because a large part of the weight of a tomato comes from water content.
Aquaponics is the production of plant crops utilizing
the waste water and organic matter derived from the
production of aquatic animals.
Since the beginning of time farmers have used
the manure from farm animals to fertilize their
crops. Aquaponics does the same thing only
with a twist.
Global Aquatics was one of the early pioneers developing the first systems in 1986 to turn fish waste into
(Click on the picture for a larger view)
We have a lot of other prepared materials about fish farming and aquaponics, including some spread sheets, to share with you at
no cost. Just send an e-mail, call or text and ask for more information.
Whether you just want a profitable hobby, just feed your family, or become a commercial full time grower, we are here to
help you. Our growing systems can be tailored to meet your needs. Everyone gets free, unlimited, consulting help.