Backyard Aquaponics
A place to discuss aquaponics

Newbie here,
Been running AP projects for almost 2 years now.

Good day,

Recently i've gotten hands on a piece of land open for our usage with 5 large concrete tanks.
Originally they were supposed to be used for acid baths for furnitures, owner of the factory can assure me they never had any acid in them.

Fast forward a decade of years, and now it's all gunked up rainwater filled tanks.
The current care taker of the land has succesfully grown tilapia's in it. The water is pretty full of gunk and algea but the frog/fish activity tells you there is potential.

Tested the water, 8.2PH hardly ran up to 0.25 ammonia, no sign of nitrates or nitrites (my guess it's been consumed by the algea)


My question now is,

Is it possible to clean out the algea and possible sticks and junk in the tank and prepare it to be our AP-systems water?
Are there people who have succesfully converted (concrete) fishponds into AP's?
Would it be a better choice to drain it out and start fresh with a new water?

If it's raw concrete you might run into issues with constant high PH issues, but also might depend on the age of the tanks. Older might be more stable.

If you're inclined, you can drain it, clean it, and paint it with a pond liner paint. That'll solve it for good, and give you a nice fresh start. Or pour hydrochloric acid in, and keep the PH around 5 for a month or so, adding more acid if it creeps up, this'll eat all the stuff that brings up the PH.

Otherwise, hook it up, and see how it goes.

I'd also think up some sort of lid to block out the sunlight, too much algae will cause issues.

I'd love to see some pictures.

Fairly large tanks, Was planning to start off with one and build up from there.

Cover should be in place, going to build a shack over the tanks. Torrential downpours here can fill up a tank in an hour or less.


Tanks seem old enough to be totally stable, but reading a lot online about concrete not being the best of choices.
Maybe start looking into your idea to acidize it. Commercial grower here told me about the same thing just acid wash any concrete and you're good to go

As visible in the pictures you can see that there is ample land available to grow some food. Needs a lot of work still though

Looks like a great start.

Make sure you start a system thread, I'd love to see pictures of it all coming together.

I wish we had that sort of rain here.

it worked for PLJ and his big concrete tank.

i would paint them with pond paint.

viewtopic.php?f=18&t=12883&hilit=big+concrete+tank

those look great wow what a score. Did the previous owner say how it went with the Tilapia. How many years ago was that?

I don't know that I would dry them out enough to paint them, it may just destroy them.
I would think they are stable enough now for pH not to be a problem.
Likewise I wouldn't Acid wash them - why rip the surface back to fresh concrete?
Just my feelings - I have never run fish in concrete tanks or ponds but have had a
few bare concrete rain and stock water tanks over the years that where no problem
at all being over 5 years old when I ran the property they where on.

Just clean them and start using tanks that old shouldn't be a problem

I'm going to +1 F&F's comment.

Not because I have any experience on this subject, but because I want to see project unfold ahaha

Any experience or just wanna see it happen too?



I will keep you guys updated, first off all now that i've seen the land I will have to start poking the right people for investments and make our first initial setup.

Location wise it's pretty amazing. Within 10Mins of 5x 5 Star hotels. 365days sunshine, 25-30 celsius average temperature year round.

In Australia theres thousands of concrete stock troughs with fish in them

lol if water test is ok.. what sense wasting that water if its only rain water... I'll leave algae.. clean out any suspended materials with a net and add a filtering system to do the rest... seeing there is algae them there os a high possibility that the water is already cycled to a point... however if there is alot of solids on the floor of the tank.. then u may have to drain it down to clean it.

when you put fishes in they will gladly eat the algae especially if they are tilapia...

agreed with cookie, with the depth of those tanks >1m algae won't be a problem once you get the water circulating, just clean the excess out with a net and get some oxygen and water pumps circulating the water. Some big airstones could help break down the biosludge on the base of the ponds or grab some pond bacteria from an aquarium/pond shop to do the work.