Backyard Aquaponics
A place to discuss aquaponics

I want to make my grow beds, fish tank and sump tank out of wood and line them with dura-skrim, I will have media filled grow beds 4 feet wide and 1 foot deep and totaling 75 feet long. I need to know what size fish tank and sump tank to build (should I build 2 sump tanks for better filtration?), also what size pump and what kind of pump.(1.5 H.P. pool pump or submergible) Should I bury the sump tank to about 4 inches above the ground. and pump water from the sump tank to the grow beds and the fish tank and gravity feed water from the fish tank to the grow beds then back to the sump tank. Does the water need to come from the bottom of the fish and sump tank. I want to raise as many fish (talipia) as I can, but don't know how much I can. Please Help. THANKS!

Hi Mountaintop.. Ummm, how have you figured out your growbed without knowing what your fish tank and sump are going to be? You sort of need to design the whole thing all at once really. I'd start doing a little more readying around the forum, no one can really tell you straight out what sort of system you need, a lot can depend on your requirements, your needs, your skills and your climate.

That is a lot of grow bed! 300 cubic feet! That would mean that you could keep 300 fish. The next step is to size the fish tank to make that number humane on the fish... According to the yellow book on aquaculture, for tilapia that would be at minimum 500 gallons. I feel that that number is rather tight, I would go 1000 gallons. You definitely want to remove the waste at the bottom, so an SLO or a conical bottom with a bottom drain would be the wise way to go. I would then use gravity to feed the grow beds. For that size I would either go with constant flood, or use indexing values to flood and drain the various chambers at different times. If you use siphons you would need at least a 900 gallon sump because there is the possibility that all of the growbeds could drain at the same time. With constant flood, or indexing valves, you have more control over that, and can use a much smaller sump. The pump would then pump up from the sump to the fish tank. As far as pump sizing, you need to be able to turn over your fish tank at least once per hour. That means sizing it to take into account your head losses. Then you want to find the most efficient pump for the volume at the head you have. It is wise to spend more on the most efficient pump, otherwise you are going to spend it on your electric bill.

Thanks for your reply. I'm new to aquaponics, although I have been researching about it for about a month now. I sold our 18x33 above ground swimming pool because we hardly ever used it and are going to replace it with a 20x30 hoop greenhouse. We will be putting the grow beds in the greenhouse and the fish tank and sump tank in the carport next to the greenhouse that we will be enclosing and insulating.
I'm not exactly sure what a SLO or conical bottom is. Is that a bottom that is angled so all the fish waste collects to that one spot so the pump will get most of the waste?
If I constant flood the grow-beds, would that cause the roots to root rot?
I'm not exactly sure what indexing values are? Do you know if a submergible pump is better or a pool pump?
Thanks for all your help!

where is Hendersonville?

You should definitely use the search function up top to find out an SLO and indexing valves are. As far as which pump is better, neither, it depends on your application. Again, find the one that moves the volume of water you need, at the head you need, with the least mount of wattage.

Do some more searching and re-searching.
What caused you to decide on a 75' long grow bed?
Are you in a location where termites don't exist?

My site has some blog posts I might recommend for helping you get started in learning.
http://www.aquaponiclynx.com/tclynx-blog-index-2

Here on BYAP, I normally recommend reading the Basic Info Section and the Useful info section and then picking a few of the big long member system threads to read all the way through so you can learn from some one else instead of having to make all the mistakes for yourself. If you can ask around or find a system thread that is for a similar climate or situation to your own, that could be useful (I don't know how to recommend one to you since I don't know where you are.)

Basically, I would say get a fish tank that is half the total volume of your media beds (or several fish tanks that add up to half the total volume of your media beds) and about that same size sump tank. Which will give you a 2:1 ratio of grow bed to fish tank which will allow you to go about the max stocking on the fish without having to deal with liquid oxygen and other craziness that isn't appropriate for backyard food production.
As noted, up to about 1 fish (that could grow out to 1 lb) per cubic foot of media as long as you have enough fish tank for that number of fish. I know of people who will crowd 1 tilapia per 3 gallons but I prefer the more sane number of no more than 1 fish per 5 gallons of fish tank for grow out with small fish like tilapia.
IF YOU GROW CHANNEL CATFISH, DO NOT STOCK THAT MANY! Yes I'm shouting. I have too many times had people come to me after their catfish are all dieing because they way over stocked the catfish into a brand new un-cycled system as if the poor creatures were tilapia and while catfish are great aquaponic fish, if you abuse them that way they are likely to start dieing on you. Channel catfish can grow 3-5 times as big as tilapia in 12 months time and it is really unfair to the creatures to stock them into a system designed for a quarter the mass of fish.

If your climate or water temperature are not likely to stay over 70 F naturally, I do not personally recommend tilapia. They don't really eat/grow much when the water is below 70 and are therefore not providing nutrients for the plants. I'm in Florida and I wouldn't grow tilapia even here unless it was a RAFT system inside a greenhouse with a free source of some heating for winter. Problem is inside a greenhouse here in summer you need active cooling to grow much of anything.

Thanks for your reply, I live in Hendersonville NC. I am planning on using treated wood for the grow beds. I bought a big propane greenhouse heater from graigslist that came out of a 20x100 feet greenhouse. I am also going to buy a wood stove for the greenhouse and try to heat the greenhouse most of the time with the wood stove. It does get very cold in the winter, I live in the mountains. What type of fish do you recommend. Thanks.

I personally like Channel Catfish because they can get fairly big and are relatively easily available through most of the country. They can survive cold (as long as it gets there gradually) and also very warm water (as warm as tilapia can) and did I mention they can get nice and big? They also keep eating down to a water temp of about 55 F though you will gradually taper off feed as the water temperature drops.

Bluegill are another good fish for a wide range of temperatures and they are good eating though they don't usually get very big so you have to clean a mess of them for a meal compared to the catfish. They do have scales so are allowed for most dietary rules.

Some people grow Bass but I've never gotten the impression that they are such good eating even though they are popular sport fish.

Now if you are in the mountains and can expect to keep your water cool enough in the summer, you might be able to do Trout but those might be better tried after you see what sort of water temperatures your system tends to keep.