Backyard Aquaponics
A place to discuss aquaponics

thanks for the encouragement skeggley, but I think it is beyond slow growth.

I set up a second system (AP02) which was a old aquarium which I peed in months ago otherwise it has got nothing except green water. it has 3 small GB total about 15L

basil planted seedlings plated 2 weeks ago in AP01 and AP02 first pic is AP01 second AP02!

Here we have some pumpkin plated in an old dirt bed which was prepared by ripping out the weeds, or most of them, no fertilisers, mulch, compost, nil.

First shot is in dirt garden, second shot is pumpkin plated same time AP01.

pretty depressing really isn't it.

We have all been warned that the first years growth isn't great and not to expect miracles slowboat.
Reading through countless system threads the majority have a less than impressive first season then action starts and continues to improve each planting.
With the money, time and effort I've put into my system I need to keep positive as do you.

I am still positive it's just that I don't want to get 12 months down the track and somebody says:

"you should have not used this or that, heck pool water has all sorts of chemicals in it"

"plastered concrete pool, can't use that"

interesting that the 2 month old test system "AP02" has tap water and some pee the plants do better
in it than my main system "AP01" which has about 150 fish and has been running for nearly 6 months!

Maybe I should drain the water and fit a poly liner into the pool? this would be a major pain in the butt and wallet.
but if it needs to be done I'd rather now than when it gets hotter.

What does your pool system pH say? If the plastered concrete pool is causing your slow plant growth, then I would expect your pH to be really high. What about the other water tests?
And in the pictures looks like the plant in dirt has lots of sun, the one in the grow bed appears to be in shade in the picture. Aquaponics might be wonderful but the plants still need about the same amount of light as they do in other growing methods.

TC, there is Pretty much the same sunlight on all the beds,

However the ph tends to be high, was 8.4 the other day, I added some HCL to bring it down to 7.6

Also it seems the fish prefer to eat during the day, as I work from 0900 to 1800 I can only feed them morning and night.

Some recommendations are feeding 3 or 4 times a day, is it normal for fish to eat during the day?

The high pH will affect the plants. pH should come down over time. What is the pH of your top up water (after it has bubbled for a day?) If you must use acid, I would recommend applying it to your top up water and letting the pH stabilize before you use it in your system.

It often depends on the type of fish, the temperature and how hungry they are. It is still warm here so I'm feeding my catfish 3 times a day most days lately but as the weather cools off I'll usually cut out the mid day and morning feeding. My catfish usually seem to eat best at dusk so that is usually my heaviest feeding (if feeding in the evening you definitely want to keep the system running overnight, none of that shutting the system down at dusk to save electricity or stop the noise if you are feeding them at night)

But it is more important to feed consistently, if the fish are used to eating twice a day and they can eat enough during those two feedings (especially if you can hang around and make sure they are eating as much as they will in 15 minutes) and if you are feeding high quality high protein feed meant for fish in recirculating culture, then you are probably doing fine. There are feeds out there meant for ornamental ponds or aquarium that are designed to feed the fish just enough to keep them healthy but not necessarily to grow them and those are designed to impart the least possible amount of nutrients to the water and thus reduce the amount of maintenance and water changes the pond owner or aquarium keeper must do, those feeds are not necessarily going to give you good nutrition for your fish or your plants. Other feeds are meant just as a supplement to a natural pond diet and they are not a complete feed they are just extra "junk food" to help fatten up fish in a dam or farm pond that are mostly eating a natural diet and they are not great for aquaponics either.

Crikey! I shudder to think how much feed my Rainbow Trout could knock off in 15 minutes! Their twice daily feed of 400g of 7mm pellets disappears in 6-8 seconds!

In that case, you can start upping their feed a bit at a time (be careful and watch your water tests, don't go suddenly feeding them 5 times more feed all in one day.) Keeping an eye on your water tests increase feed a bit each feeding. So that might mean you increase their feed a bit for the morning feeding and come evening do a water test to check the ammonia and nitrite levels before you give them the evening feed. If you see ammonia or nitrite elevate much, then you know you shouldn't feed more than that for several days till your bio-filter catches up to the load. If the ammonia or nitrite get say more than 0.5 ppm you might want to hold off or at least drop back the amount of feed a little till the bio-filter catches up. You may find a point at which your bio-filter can't handle any more if you have too many fish or too much fish tank compared to the amount of grow bed you have.
But by that point, you will likely have a lot more nutrients available for your plants.

thanks TC, the gold fish are good feeders but the Silver perch are a bit shy and don't seem to like coming to the surface to feed. The weather is starting to warm up here now, so hopefully I can get them to trained to surface feed.

As many of them are still small I grind up some of the 3mm pellets. the small SP wait for the feed to sink and grab it on the way down, only a couple of the larger ones (70 mm ) will dart to the surface and grab some feed.

in regards the pH the pool is concrete with a plaster finish, it has always been tending to high pH.

I am not sure what the plaster finish is comprised of, but it could well be making the pH rise.

I think the "puddle" also has high pH issues PLJ?

I think would be possible to fit a poly liner into the pool, albeit pretty tricky with water and fish in situ.

Hey slowboat
Concrete pools are usually plastered with a strong render mix of about 5parts yellow sand 1part lime 1part cement.
Then filled usually without any sealers or waterproofing

Thanks, TCLynx, but I am at the limit of the filtration capacity of my system. Actually, you may have confused me with with Slowboat, whose system thread I have infiltrated with my comment.


I haven't tested the Puddle for a few weeks but the pH had come down from its earlier constant high readings. In fact, the parameters were pretty much ideal as I recall but plant growth in that system is similarly slow to yours, Slowboat.
My theory is that the larger the volume of water in a system the longer it takes to properly cycle and produce the plant growth that we expect. I think I overcame this delay hurdle with my big concrete tank system by underfiltering it in the early stages (of fish presence) and relying on the dilution factor to maintain adequate fish health. To this end I only fairly recently connected my grow beds, and just three of them. Despite the harsher winter/early spring conditions up in this neck of the woods, this system has produced excellent plant growth - much better than the poor old Puddle in its cushy metro location.
I think there are strong parallels between your pool-to-pond conversion (PTPC) and that of the Puddle, including the type of fish providing the 'power' behind it. The concrete tank system, on the other hand, is powered by a large number of actively feeding Rainbow Trout, which is a far cry from a few Goldies and some small, not so hungry Silver Perch.
I have stopped stressing about the Puddle because I am confident its 'time in the sun' is yet to come. So, too, your PTPC- I only hope that I have conveyed some of that confidence to you.

If a concrete tank is indeed keeping the pH higher than the nitrification can bring it down, it may well be worth a major overhaul to seal it or line it some how. If the pH will naturally get down to 7.6 on it's own without constant use of acids, then there are some things that may still do ok in the system but constant potassium and iron supplementation will likely be required for most things. I my old system with the shells as media, pH would not get below 7.6 under normal conditions. I was still able to be quite successful with certain crops. Watercress in cool weather. Water chestnuts in hot weather as well as bananas, papayas, Jicama, Lufa, broccoli, kolhrabi, Kale, veronica, lettuce, basil, leeks, aloe, and others. As noted, my main problems seemed to be Iron and Potassium, I had to be dosing weekly to keep plants from having real issues with their lack or lockout.

Waiting on Nate's next video on nutrients and carbonates,

What do carbonates do to the system?


water test today pH back up to 8.

added another 150ml HCL.

Am thinking that the poly liner will need to go in, wish I had done this first.

my cunning plan is to remove all "furniture" from the eg. FT yabbie homes and such.

Then get a 6m x 6m x 200 micron poly liner and slide in the FT trying to get all fish on top of liner.

then secure around edge with a batten "nailed" into the concrete.