Backyard Aquaponics
A place to discuss aquaponics

Hi all,
A few months ago I began the conversion of my 55000 litre swimming pool into an aquaponics system.
It'll be interesting to see what you all think of the setup.

Ive got a 33000 litre/hour water pump to do the hard work and the pipes split into several different paths, each with taps attached to control the flow rate for the grow beds, the waterfall and the filtration bed.
Initially I just had one small filtration bed full of gravel and water plants, a few 200 litre containers full of gravel and water lilies to help with filtration and some floating pots with water chestnuts, kang kong, watercress etc.
I had 100 silver perch fingerlings and 46 koi fingerlings and everything was going fine once the system had cycled, the fish were growing, the plants were growing, the dust from the gravel was settling and the water was clearing nicely. I bought a water test kit and all the levels were fine but the ph was a little high. Then one day I was outside and couldn't see any fish, it turns out a passing cormorant had decided my setup was the perfect buffet and had eaten ALL the fish.
So I bought some netting, jimmied up a cover, bought some more fish and used the break to add a couple of beds.

I've got 150 silver perch and 8 koi at the moment but plan on getting 92 more koi and another 100 or so perch. They've been in for a few weeks now and the water is still pretty cloudy from the new beds and the fish stirring things up down the bottom but the levels are pretty good (apart from the ph being a bit high but I presume that will go down as the system settles).

So that is pretty much it.
I'll add some photos at some point and I'm always open to questions, feedback, advice or suggestions.

It's good to be part of this awesome community at last.

Hey Brad..... Sounds interesting, have you got any pictures?

Bugger about losing your fish.. I'd be holding back on getting any more for a while, that's quite a lot of fish you have already..

SHOW OFF

Hi earthbound,
It sounds like a lot of fish I know, but because there's so much water and I've got 4 beds there's actually a danger of not having enough nutrients for the beds. At the moment the fish have about 350 litres each whereas it's recommended that they have about 10-15 litres each, there's no way I'm ever going to get to that number as I'd have 5500 fish in the pool but I'll definitely need to get a heap more to bump up the ammonia/ nitrite/ nitrate production.
One of the challenges of a big water supply I guess.

I'm afraid that's been dispelled as a pretty bad recommendation though Brad... It doesn't really translate well to think of number of fish in litres of water, it's more to do with number of fish per ltres of growbed media or square metre-age of growing space. You could throw in a good allowance for algae growing on the side of your pool though in those equations.

I would be more worried about how much filtration you have.

For example. The BYAP growbeds are 500 litres in volume. For each bed of this size you can have 25 fish with a harvest size of 500 grams each.

A large volume has the advantage of stabilisation - for example the temperature wont change so rapidly.

Edit: Beaten by the master.

Yeah, 5500 fish in a pool like that would be kind of crazy....

Although it'd be pretty exciting at feeding time!

Interesting to change the equation to grow media, I'll definitely keep an eye on it once the system has cycled.

So if I've got the suggested number of fish for the grow beds (as worked out with the fish to grow media ratio) wouldnt the algae, lilies and extra water lessen the amount of nutrient making it to the grow beds? Effectively 'watering down' the nutrient going to the beds?

Larger systems take a while to settle down and cycle. If you put in too many fish to start with it is a lot harder to make adjustments.

Call the pool a pond, and float some rafts with plants on top. No need to pump the water anywhere probably.

Am I right?

later,

jeff
c

You still have to pump the water to get out all the fish poo......and keep the systems water moving somehow. It wan't just lay stagnant, it will become anerrobic That is my understanding anyhow.

Sounds like a great project Brad, pity more people don't do the same.
You didn't mention if you intend keeping the pool as a Natural swimming pool or if you intend converting totally to an AP system. As a natural pool your stocking would be fine if you intend converting to a full AP system I would suggest increasing the fish stocks but keep it at safe level (better understocked) and add nutrients to the growbeds.

yeh still need solids removal and aeration, and filtration if you want to stock high levels of fish

Hi desertrat,
it's definitely a shame more people don't do this, I've met so many people that don't really use their pool enough to justify owning one but they just keep feeding it chemicals and electricity.
I'm going the AP route rather than the natural swimming pool, although I saw a natural swimming pool up in kalamunda and it was truly awesome.
I'll definitely add more fish but I'll do it in stages and keep a close eye on the water levels as I go. I'm only a few weeks into this version of the system (after the bird attack!) so once it's cycled properly I'll start putting a few more koi and silver perch in to get the nutrient levels up.

Yeah the water definitely needs to go somewhere. In aquaculture they tend to drain at least 25% of the water to get the ammonia out. The woodvale fish and lillie farm people suggest that a 'normal' fishpond should cycle it's entire capacity every hour to avoid stagnancy. I'm not pumping that much as I'd need a jet engine in the back yard to handle the load, but I'm pumping about 30,000 litres an hour, which is still massive.
I've got a few floating plants and the are doing quite well, as were the water lilies when the weather was warm. There's a fair bit of aeration going on too which definitely helps clear up the water, I think it would get a bit 'swampy' without it.