Backyard Aquaponics
A place to discuss aquaponics

I'm starting this thread as a re-direct for a Hijack.

An Aquaponic system needs some form of the following things.
1-fish tank/water for fish
2-bio-filtration (to convert Ammonia to Nitrite and Nitrite to Nitrate, as well as other mineralization we don't dwell on as much.)
3-solids filtration
4-plants to take up the nutrients

Many people will ask how much fish tank do I need which always leads to the questions of how much grow beds for an amount of fish tank, and so on.

Around here most of us are running flood and drain media filled grow beds which fulfill basic needs 2-4. I know the basic numbers for those types of systems. 3 kg of grown out fish need about 100 liters of media filled flood and drain grow bed supporting it. (That is probably around 6 lb of fish to 25 gallons of grow bed.)

When people talk about ratio, they are talking about Grow bed to Fish tank so a 2:1 Ration is say 200 gallons of grow bed to 100 gallons of fish tank. A 1:1 ratio would be grow beds equal to the fish tank.

(Yes, you can do many other methods but since I don't know as much about the exact workings for other methods, I can't be much help there.)

A question I saw lately was asking about growing fish mainly and not very interested in growing plants. First, the fish still need enough bio-filtration and solids filtration to keep them healthy. This can be done with aquarium type filters if sized correctly or pond type filters but I don't know much about that so can't tell you how to go about it in particular. And if one is going to keep the nutrients in check in such a system by doing water changes, then it is really not Aquaponics, however, your dirt plants would probably really love the rich fish water. If doing water changes all the time to keep the nutrients in check, then one needs to have a very good source of water that isn't treated with chemicals like chloramine or chlorine.

3450 ltrs of gravel
2000 ltrs clay
200ltrs bioballs
100ltrs bioballs(inwater filter, high water turn over)

50000ltrs of water in system, avg

47 silvers avg 35cm ish
53 catfish avg 20cm ish
6 goldies avg 35cm ish

Ammonia 0
Nirite 0

just read the thred,
years ago, when i joined, i read some where it is a ratio of
2gal of media : 1gal of fish water : .5lb of fish in grow out.

i not saying grow .5lb of fish in 1 gallon of water, so more like 200gal:100gal:50lb, or 100gal:50gal:25lb ratio.

is that right?

Yep that sounds about right.

thank you TC.

but having that being said... can you have a growout size of 25lb of say tilapia in only 50 gallons of water (givin the filtration was suffent, not like my system )
and what is a good plate size tilapia, like 1.25lb or more?

-df

Yes, you probably can, but you will need lots of worms in the growbed and, probably, some extra aeration. Easier to have half the fish load.

I've never managed 1.25lb, but mine were decorative rather than meat. I've heard 1.25lb (about 1/2 kg) quoted...

so after some reading, and scrounging for parts, i think i've found;
1 120 gallon fish tank (about 450 liters)
2 55 gallon drums cut in half for grow beds (about 375 liters)
2 flood tanks/floating beds

so if i don't fill the fish tank, i could be pretty much at 1:1
so about 30 to 40 fish (tilapia or yellow perch)?

what kinda pump volume?

it's late and i'm finally allowed to go home from work, g'night ya'all

"If I don't fill the fish tank"? I don't follow....


If the tilapia are small you could do fine. Even better if you can get it cycled ahead of time..


You need one to pump at least the volume of your fish tank each hour at whatever head height you have. I'd go double since pumps never seem to pump as much as advertised.

what i meant about the fish tank not being filled all the way to the top, so, in a 120 gallon tank, i'd have 100 gallons of water-

hoping to start the build next weekend, after gassing out water, i figured i'd pick up some feeder goldfish to start everything circulating before buying fingerlings..

i've been driving the wife nuts about this stuff, but last night when i got home from work, she said she saw a centipede (or silverfish) on the bed, and that she brushed it off and it was on the floor.. i said,, mmmmm fish food, she laughed and said she thought the same thing! lol

have a good one
k

the amount of growbed gallons doesn’t matter as much on how many gallons water your fish tank has, but more rather the amount of fish growing, your growbed needs to be able to handle the fish wastes, and keep the water clean and clear.
so buy that, you can have your 120 gallons of water.
but if what i was saying just about right: 100g:50g:25lb GB:FT:Fish

you would have a: 100g:100g:25lb
now to have 40-50 grow out fish(tilapia) you would need 200g of growbed... so what i am saying the grow out ratio is 25% of your grow bed volume in gallons.

now pump volume and circulation, and aeration all matters on your fishtank size.
but to have a efficient ratio would be 1:.50:.25 simple...
so growbed volume/.5 for fishtank volume/.5 for fish in pounds.
i hope that helps.
-df

yeah, it's starting to become a little clearer..

hopefully this weekend i'll be able to get my growbeds, and frames built, maybe pick up the fish tank too

still coming up with the design in my head, but thinking 2 barrels in half for 4 growbeds, unless i find something cheaper than $15 for 2

still gotta look at pump info to size it, i have a little time yet

thanks for the info, it's starting to come together

you should get around a 300-400 GPH pump, just to be safe...

and do you have your own thred on member systems? if not, do so, is nice to have and keep track.

On the subject of ratio's I believe we should be comparing water volume to growbed volume, not fish tank volume to growbed volume, because most 2:1 systems involve a sump, which is really just a separate part of the fish tank. A true 2:1 system is only possible if stage filling multiple growbeds by either separately controlled pumps or using a sequence valve (spider valve), this system maintains adequate water in the fish tank.

I think I may have mis-replyed earlier to something.

Ratio should be something like 1 lb of fish per 5 gallons of grow bed, not the other way round.

As to the 2:1 ratio. That is comparing Grow bed to Fish tank. You can't have a 2:1 ratio without a sump, at least you couldn't until the Aquaponics indexing (spider or whatever) valve came along (other than the special people who managed to automate valves in the past.)

So you might still have a 1:1 water to grow bed but 2:1 fish tank to grow bed.

Also, the point of the fishtank:growbed ratio is to make sure the water in the fishtank gets circulated through the growbeds frequently, I believe. I don't care if you have a sump that is 75% of growbed volume or 100 times the growbed volume, I want the fish getting fresh water...

On that same point, some folks have suggested that rather than fishtank volume one should base circulation and growbeds on kilos of fish or, even better, on feed rates, since these are more apt to be accurate predictors of the amount of waste that needs to be dealt with.