Backyard Aquaponics
A place to discuss aquaponics

When I type "swimming pool" under "Search" the website comes back with lots of forum topic threads, but I cannot locate mention of using a below-ground swimming pool to grow fish and plants. I am convinced lots of people have such a system and I'd love to learn about their experiences.

Cheers
Adrian

That's a big pool to start with Adrian.... and will require a lot of filtration.

How much will depend on how many fish you stock.

Getting a system that big to cycle will be no easy task, and again will depend on the capacity of your growbeds (filters) and stocking density.

Could I suggest that you would be better served starting with a much smaller and simpler system at least 10% of that size.

My other suggestion would be to set aside a month and read through the wealth of material here on the forum.

Rupe, How about only filling the pool 500mm deep, and putting more water in as Adrian wishes to expand?

KP, it's more a matter of determining size to start, experience available but more particularly the amount of filtration available to start with and to expand to.

First question to Adrian is whether or not he intends to utilise the pool as the basis of an "aquaponics system or just as an "aquaculture" pool?

Even 10% of the pool size is 7500ltrs and as such would require at least that much growbed capacity in an aquaponics system to filter that amount of water....

And thats a 1:1 ratio best practise and very dependant on stocking rates.

Now the advantages of something that size (7500ltr) is stability and flexibility in terms of temperature, pH, and other parameters and the ability to react to changes.... i.e it takes a while for anything to get out of whack, so you've got time to react and apply changes....

The opposite side of the coin though is that similarly it takes a long time to shift things in a desired positive direction.....

At 75,000ltr you're talk serious quantities of anything to get a resulting change....

You're also talking major filtration, plumbing, and pumping requirements....

And as I said to provide a minimum of 75,000 ltrs of growbed filtration would physically required a large land area..... Not a normal suburban backyard I'd have thought.

And then there's the question of just what do you do with the sheer volume of vegetative food and fish produced.

Are you intending this to be a "commercial" venture Adrian?

If it's just for home then, yep as KP says you could only partially fill the pool, or fill it and only lightly stock the pool..... still a lot of water to move around and deal with....

I think you will have to be very specific in your aims and plan accordingly.

Oh and a fat wallet might help

Hmm i hadn't quite grasped the enormity of the pool...

based on my calcs with a 300mm deep grow bed and ratio 1:2, you need 6m² GB for every 1000L FT.

So Adrian will need 75*6m² = 450m². That is a house block... I wonder if he's on a couple of acres?

Adrian, can you section off your pool? APers have had difficulties with big tanks, and find it easier to manage a series of smaller tanks, to separate age and species.
Not much chop if you eat half your fish, but can't put in new fingerlings, cos they'll all get eaten. (perhaps too much chop )

I agree with Rupert mate, start small. I didn't and I'm still not off the ground 1 year later... big mistake. Also, read lots, I didn't do that either, and have already replace half my plumbing due to silly mistakes of the inexperienced.

Perhaps use your pool to store rainwater until you're confident enough to go bigger, that way you have free topups.

There's a heap of experience here.

Isn't the quantity of fish a determining factor? I am aware that if I multiply this large volume of water by whatever stocking ratio various people suggest, I'd have tons of fish. Which isn't what I'm after. I want to be able to grow myself a kilogram or so of fish a week to eat.

Right now, the dozens of little fish I have in the pool are thriving--without any filtration at all.

Adrian the reason they are thriving is it takes a while for the toxic ammonia to build and nitrites. However left alone long enough they will breathe and crap themself to death!

So in short they may be ok now but when they start to look like a hammerhead shark and die remember fish die

BTW if you want to see my insanity check my system and how high I run levels with fish. As Rupert says Premeditated Fish Murder!

Regardless you will need to have a way to cycle that water in a decent fashion to pull out the toxins. I am sure it can be done but plan it out and kill some fish in the process. Thats what I do


Btw Kuda, Thats only 4500 square feet or .1 acre do not really need too much land to do it just planning.

Dozens of little fish are ok, because of your water stability. You have HEAPS of water, so it goes bad VERY slowly. They water should go bad eventually, unless there are plants or something growing to remove the nitrates and phosphates.

Enough bacteria grows on the walls of the pool and other surfaces to support these small fish. This luxury will end if you put larger fish and more of them in.

1kg fish /week = 52 per year
12 - 18 month growth period means you will want about 100 fish in your system at any time, requiring a minimum 2000L of water. and 4000L of GB.

however, if you don't want all 52 at once, you will need to have many batches of say 20 at a time. These you will probably want to separate. Can you do that with your pool?
I wish you the best of luck, but as Rupert said, you'd best design this ultra well.

If you already have those little fish, creating fertiliser, I suggest you get a growbed up and running, pumping from the pool and see how you go, without getting expensive fish. You should feed the little fish to aid the process.

However because you have such a large body of water, everything will be dilute. So your pumping rates into the GB may have to be high to get the same advantage in your GB as with a smaller system. (can some1 confirm?) Also based on that assumption, if you run your system at low pump volumes your ambient nutrient and ammonia and nitrite levels will be higher than for a smaller system with the same growbeds - maybe.

True, true Adrian, didn't know what your intentions were, especially as you mention that Brett O'Brein was assisting you.

Yes a small number of fish will survive sommetime in a huge pool without filtration. Ultimately though you will encounter problems due not so much to ammonia build up, but algae formation due to exposure to sunlight, uneaten food and increasing nutrient levels...

How long will it take.... how long's a piece of string....

Depends on, how many fish, water temp, whether you are providing any filtration, any additional oxygenation provided, amount of feed... etc etc...

By the way, Adrian, if you want to search for info, click the "Posts" button rather than the default "Threads" button..... bet you find some results then.....

Happy reading

and the search function works better on single words than phrases. Happy reading

I think you'd be much better off just building a small system, about the size of Joel's systems as in the book and like the one you saw at Faye's.

Those size system will provide roughly what you're aiming for and give you a good idea of the space needed.

They're also managable for a novice and intermediate aquaponicist.

Thank you, RupertofOz, Jamie, KP and SD.

I am vastly impressed with the friendliness and readiness to advise me. I'll start with a few fish, three or four small tanks and a good-size pump which I scored already. If it goes well, I can add, cautiously and slowly...

That's what the forum is all about and what we're all here for Adrian....

And believe me you could spend a long time here just reading and absorbing peoples ideas, experiments, successes and failures.... but it would be worth the read

Hey I started with 100 goldies in a 18 gallon tank! Add a bit of spice to that diet

Although Honestly I have learned that the method of when in doubt add more fish does not always apply when you go to the extremes.

One thing I would advise you get that I made the mistake of not doing is getting all the proper testing stuffs. Ammonia, Nitrite, Nitrate, PH etc.

ADRIAN, your problem with the search is that you need to select POSTS instead of TOPICS. lower left hand side

enjoy

PS i think i worked out that at full density julies 40KL pool would support a few ton of fish.

You could match the number of fish to the growbed size, all it means is that it will take MUCH longer for nitrates to build up initially, after that its an equilibrium thing.

you could always stock the fish and leave the beds fallow for as long as it takes