Making bio filters

[CQ AQUA]

Hi, is there any sort of guide on what size filter for what size tank and fish loading.

I'm making my system myself as much as poissible. Through my work i've got access to plastic 205 ltr, 20 ltr drums. I think they'll be handy but am unsure how to make them and how many of what size.

The system will have a 4500 ltr tank and i want to run as many growbeds as i can fit ( how many could i do ??? ). And how many fish could i stock?

I'll look forward to your replies.

Regards, Jim

[fishfood]

Hi welcome to ap madness for a rough figure 2 to 1 is a rough figure most of us work on [4500 fish tank 9000 litre beds] it depends on fish load plant load etc[ the more fish the more plants you can have also size fo fish] just a tip look at established and new systems thread and read them all
sit down and look twice defore doing things [its a lot easier to do it once]
i am running 3, 1000litre tanks all using the same water [ 2 different tanks of fish and 1 tank smaller ones] gives a constant fish load otherwise when you harvest all your fish [you have nothing to carry the plant load]
ask a lot of questians some won will be to happy to answer
enjoy the trip
currently i have 30 silver perch 12 in long 70 silver perch2 to 4 in long 50 trout 6 in long trout will be ready before xmas
[to hot in qld for trout]

[CQ AQUA]

Maybe i've asked the question too ambiguously.

I'll be using 8 2mtr x 1mtr x 400 mm grow beds but i'm concerned they won't be enough. Thought's please.

So what i've considered is having a bio filter after the grow beds and before the sump or on a seperate line. Any thoughts on which will be preferable to achieve a good result?

I'll rapidly be aiming to have the system running near full capacity so don't want to overload things.

Thanks, Jim

[fishfood]

If useing a seperate biofilter it should before the beds

[Hamish]

Yes - before the grow beds. Or you could do what I do and have the biofilter (in my case a canister filter) running off the fish tank seperate to the water pumpin through the grow beds. This way you have backup if your main pump dies - and you can also seperate the tank from the grow beds if necessary and still have biofiltration for the fish.

[nick]

you will be fine with the growbeds to fish tank size. by my calculations you have 4000litres of growbeds to 4500 litres of fish tank. As a biological filter that volume of growbeds will be fine. I think traditionally 3kg of fish per 100l of growbeds is the figure used so on that you would be looking at 120kg of fish in the bed.

You do not need additional filtration if you are running about this number of fish. Also to help you thinking, this could mean you could get 300 fingerlings and grow them to 400-500grams and then harvest half of them out at this time and let the rest grow on to 1kg anf have fish to share.

I think the problem with these systems if you do not meet the classical 2growbed litres to 1 fish tank litre, is more that when you get to high fish loadings you have trouble take out the nitrate with your plant growth. So you have to stock heavy feeding plants at high densities t make up for the less volume of growbed.

This could be as simple as adding an NFT system at your peak growing times and using water that has come out of the growbeds so it has been filtered, and growing lettuce and silverbeet.

any way hope this helps, Nick

[Jim Bedford]

Hi Folks,
I'm following this thread with interest and am a little confused. Jim has growbeds @2x1x0.4m=0.8x8 of=6.4m3 =6400L minus the scoria or other media displacement. Sorry, I'm a bit slow on the uptake here, and not in a rush, so am doing as much research as possible. Nick, how did you arrive at 4000L growbed?
Thanks for your patience and advice (and these sites you find, Hamish, are very interesting, Cheers)
Jim Bedford

[Murray]

The volume of fish tank to grow bed is just that, the total volume. The volume is not talking about the water volume in the grow bed, but the total volume of the bed, media and water. You don't need a bio filter ...as posted above by Nick, FF and Hamish, but it does help and is a bit extra insurance to help balance the system. I have a canister positive pressure bio-filter that I shift from fish tank to fish tank when I need a bit of extra filtering for what ever reason. Very handy, but not strictly essential.

[GaryD]

Hi,

Just to weigh in with my two bob's worth......the 6400 litres of grow bed is perfect for your 4500 litre tank.

As others have suggested, you won't need a bio-filter for this system.

Gary

[nick]

i just made the assumption that they are roughly the same as murrays and they are 500l each, thus the 500 X 8 gives 4000litres, the calcs were off but the thought is still the same.