Backyard Aquaponics
A place to discuss aquaponics

Hi everyone,
We've a fishpond about 12m x 4 m holding more or less 25 tons of water. At the moment it holds koi and mosquito fish and is fairly murky. The pond has lilies and hyacinths but they are not enough to maintain the water clear. From this you can see the aquaponics would interest us. We are already moving towards self-sufficiency as we grow some of our fruit, veg, and meat. Can anyone give mean idea of what size of growbed I should construct?
My intention is to pump in sunlight and stop when not, as we have a solar system supplying our house. I do not want to use my stored battery energy.. if possible. We have space enough by the pond to put a raised growbed to allow gravity flow back. It would be easy for me to fill the bed and switch the pump off, then allow drain down and then restart. If need be l can automatically shut the drain at night and keep it flooded I or partly so. Would this work, or what issues would I face.?
Don't worry about the koi, they have been in the put for 10 years, so any cleaning I can achieve will be beneficial. However when I get the system working I would like to introduce an edible species, but one with few bones. Has anyone got any good suggestions?
Is there anything special about the seeding compost?
Regards
Chas

With a pond that has approx. 6000gal in it. Unless you have ALOT of available land for the project. You will be more likely to run out of room to plant.

Hi Floridafishin.,
land is not something I'm short on . We have 40m x 50m of flat land adjacent to the pond but there is no way we can afford to (or want to) plant such a big area. We are trying to be self- sufficient , not start a business. Our current fish stork is very low , hence the fact they can live in a totally unfiltered pond. Apart from the tiny mosquito fish (I have no idea how much their combined weight is) we have about 12Kg (26pound) of Koi.
As we get the water clean we would like to add some edible fish, pehaps tilapia.
As of this moment We have a pool of 7 sq M (70sqft) which is 50cm (20 in) deep set up alongside the pond.
This is our first "such it and see" attempt at this , as you can tell.
Chas

Your main problem will be mechanical filtration. The pond will overwhelm the Grow Beds in a very short time.
As to the size of the pump it should be sized to your GB's ie how much water you need to get through them.
This is contrary to most of the advice you will receive on this subject however yours is a slightly different situation.

Hi sleeps, do you men that the gb will not provide enough filtration for the fish pond? We can provide a pre or post filter but which is best......I would suppose the post filter, but I would like to get someone else's opinion.
Is there some rule of thumb or calculation as to the balance between fish (by weight?) and plants?
Regards
Chas

Out of interest Id check the water parameters, if nitrates are present I can't see why it wouldn't work. There are members here with water bodies of similar size to your and they grow plants quite well with minimal GB's.

thanks Charlie,
It's good to know that I'm not doing anything fundamentally wrong.However it seems to me there should be a ratio (or set of ratios) for the quantity of fish to the quantity of plants. How do other growers determine how many fish to put in the system or how many plants to put of in?
However it seems to me there should be a ratio (or set of ratios) for the quantity of plants to fish
Regards
Chas

You could overwhelm yourself with aquaponic ratios and rule of thumbs once you start looking. Search 'ratio' in topic titles only to get you started, there's also the FAQ link and IBC of aquaponics that have good info too. A members thread that might appeal to you is PJL concrete tank system and there are other pool conversion systems.

Like you said you just want a bit extra filtration and might as well grow some plants at the same time so firstly get yourself an API freshwater test kit and check the pond water parameters then add a trial grow bed and see how it goes, you may find certain deficiencies which you can treat via foliar feeding. You may also need to incorporate commercial feeds. Many variables.

Hola Chas
Your situation is very similar to Hugh’s. The man with the moat (On this site)
My advice is similar. A dirty water sump pump to an RFF ( many plans here) then to an IBC cut in half return to pool. Fill the IBC with clay pebbles or gravel.
Plant basil etc whatever takes you fancy.
Tilapia are not my speciality. However get the herbs/running and take it from there
I said basil because in Malaga where I spend a lot of time this is sold in a garden centre not supermarkets???

The problem with ponds is not your fish to GB ratio at this stage. Ponds don't just get fish crap they get all sorts of other detrius in them. If you pump straight to a smallish GB it will silt up and become anaerobic. Basically you need a mechanical filter before the GB and it will be a weekly chore at least initially to clean it.
If you dont mind a bit of work dig a trench same level as your pond with a small pond at the end of it. Make barriers along the trench to almost water level, this will act as a series of settling tanks. Pump from the small pond to the GB then return to the main pond. Would still put a smaller mechanical filter in before the GB's initially

Hi Sleepe ,
I don't think I need to worry about silting up the pool. It is at least 40cm deep. It will be quite easy to " vacuum" the bottom every week or two until the system clears up.
Regards
Chas