Backyard Aquaponics
A place to discuss aquaponics

[size=150]We are new to Aquaponics and may have started a little larger scale than most would have. We are located in West Texas and as you all know, everything is bigger in TEXAS. Our facility is at 3,000 ft. above sea level. Our first greenhouse is 20’ X 24’ (480 sf). We have room for 216 plants one level high. There is enough ceiling height to go two levels high. We are using IBC Totes cut in half and filled one foot deep, with floating Styrofoam rafts. A 20’ diameter 4’ deep above ground swimming pool is used for the fish habitat. The pool came with a reusable filter and a pump as well as a nice cover to keep the birds out. When full, it holds 8,800 gallons.

Our plan is to raise Mozambique Tilapia.

How do you determine how many Tilapia can be raised?
How do you determine how many plants can be grown?
It is my understanding that the Mozambique Tilapia will tolerate the temperature swings we have here in the High Desert of Texas. It can be over 100 degrees during the day and down into the low 60’s at night. I expect my water temperatures will elevate into the mid to low 90’s in the summer. Maybe higher. We can have relatively cold winters where it can be below freezing for weeks at a time. This winter weather can start as early as November and have a late freeze as late as March. Generally there will be two to three weeks total of this freezing weather.

Please advise whether you think we are on the right track.
Sincerely,

Circle D Ranch
Aquaponics Division


Jon B. Quick
Director of Operations[/size]

Welcome to the forum Jon

You might want to look through the FAO document on small scale aquaponics as a start - http://www.fao.org/3/a-i4021e/index.html

You'll need to figure out your filtration which should come before the IBC rafts and should include filtration for settleable and suspended solids.

I've found Lakeway Tilapia's website to be a valuable source of information about tilapia farming. https://lakewaytilapia.com/

here is a quote on quantities they recommend from their 'live fingerlings and fry' for sale page...


so based on that their recommendation is about 3.75 gallons per pound of tilapia. With 8800 gallon aquarium that would mean you COULD get up to 2346 pounds of tilapia in that pool (at about a pound a piece harvest rate that means 2346 tilapia max). However there is much more that goes in to it than just the amount of water you have. You need to figure out what kind of filtration you need to support the quantity of fish you will have, and if you were running anywhere near 2346 tilapia in the system you would have the nutrients to feed a couple acres of aquaponic beds I would think... so you need to figure out how many beds and of what size you will be able to run. If you are only running raft beds you will need some other sort of biological filtration (someplace for beneficial bacteria to live that convert the ammonia to nitrites and nitrites to nitrates). Then you should always start slow because going BIG in TEXAS means failing BIGGER if you go too fast... start with a small number of fish to allow the system to mature slowly on its own... if you put 50 tilapia in an 8800 gallon pool and let them do their thing you would probably have several hundred tilapia after 6 months (tilapia can reach sexual maturity as early as 10-12 weeks old, so by 6 months old they would be breeding like crazy).

I would start small and measure your nitrates as the population increases... once you start seeing nitrates appearing it means your plants aren't keeping up so you need to be able to add more plants or you've reached the limit of how many fish you should keep. It will probably take it a while for you to reach the point where nitrates are detectable with that amount of water.. but from what I've read it takes 18 months for a system to really mature to where you'll be getting the knock your socks off growth that everyone wants anyways...

I'm not sure this tells the whole story . Raft beds actually do a pretty good job at providing a space for the bacteria that convert the ammonia, especially once the plant roots are available for additional surface area. You probably still need additional bio-filtration though and you'll definitely need solids filtration if you're running rafts.

So which way do you use?

I don't have experience with that so I can't say for sure, but my assumption is that the surface area of the empty liner wouldn't be enough surface area for the bacteria based on school of hard knocks when I was new to aquariums... when I first started my saltwater aquarium and spent time reading about how salt water tanks didn't need additional filtration because the rock and water flow worked as the filtration and housing for the bacteria the first thing I did was remove the media from my filter in my freshwater aquarium... it ran OK for a while but then I started looking in to planted tanks and decided I wanted to switch from decorative colorful rock to something better suited for growing live plants. I figured I had a 55 gallon aquarium with relatively few fish in it so the amount of surface area on the glass for bacteria to live was quite large... so I pulled all of the old rock out and put in new media and even with the small bio-load I came home the next day to an aquarium completely cloudy due to a bacteria bloom. The ammonia shot up so fast removing the old gravel which housed the majority of the bacteria that it took less than a day for the ammonia to jump so high that the bacteria bloomed causing the tank to be cloudy and that was all she wrote everything died pretty quickly.

I guess there are a couple differences here, if you started with no media at all then perhaps the bacteria would colonize whatever surfaces you had available to do the bio filtration adequately vs. having a media there then removing it, and perhaps the quantity of plants might make a difference but I wouldn't want to rely on the plants as surface area for bacteria... what happens when you harvest a plant and those roots are no longer there? I would expect to have K2 or some other type of media in a filter for bacteria to colonize with a much higher surface area than just the bare walls of whatever beds you use. Especially if you planned on having a high bio load (asking how many fish can you fit in 8800 gallons?)

You can use either or both - Dasboots current system is an example that uses mostly the rafts but also has mineralization tanks for solids. Either way you have to remove the solids for the DWC but you don't have to mineralize them unless you want the extra nutrients.

The above ground swimming pool came with a washable filter.

If the existing swimming pool filter is not enough I could employ circulating the water slowly through a series of sand filters to remove the solids. I will also be able to vacuum the pool as necessary.

I was thinking if I needed them I would put aquatic plants in flower pots and sink them to the bottom of the pool.

With fish being our priority right now, is there another way to remove the excess ammonia/nitrites and nitrates as we expand the plant side of the equation?

Vacuuming the pool will help some with solids and a bit with ammonia but most of the ammonia and nitrites are in the form of ions which are dissolved in the water and won't be removed this way. If the DWC bed doesn't remove enough of the ammonia and nitrites you can use an MBBR/MBBF (Moving Bed Bio-Filter/Moving Bed Bio-Reactor). Since fish are currently your main concern you may want to do some reading up on Recirculating Aquaculture Systems (basically a fish only system) and Dual Loop Aquaponic systems. I think you have a fairly steep learning curve but it can be done.

For a RAS the flow goes something like this -

Fish Tank -> Radial Flow Filter (RFF) -> Static Upflow Filter (SUF) -> Sump tank -> Fish Tank...

The RFF removes settleable solids while the SUF removes suspended solids

A Dual loop AP system would take the solids from the RFF and maybe the SUF as well and would mineralize them, after which the nutrients from this would go to the plants. The water doesn't go back to the fish once it's on the plant side and is just recirculated in that part of the system. It's basically a RAS hooked to the plants going one way through the mineralizer. This allows you to have more control over both the fish and plants but requires more input from the grower.

--------

Washable pool filter . Bead filter maybe