Best concrete sealant? Advice?

[BSTN]

Hello, I have a 5,000 gallon concrete Koi pond from a house I purchased that leaks.

Last year I drained, power-washed, and dried the existing concrete. the concrete had a blue primer looking paint that was chipping off. I did my best to get a lot of it off but it was still about 70% coated.

Then I got 5 gallons of "Liquid Rubber (LR) Water Proof Sealant" after about 6 months it has begun flaking away and I see the original blue sealer or paint that was underneath. So it's not sticking. I put around 5 coats over a concrete primer.

What would anyone recommend I do to prevent the leak? Knowing that there's old primer and old LR on the concrete.
A liner will not work with my setup. I need some sort of paintable sealant. I'm even considering doing fiberglass. Or maybe just another layer of concrete over the top and seal a fresh concrete surface?

Any advise is much appreciated, I have a thriving ecosystem, spent over 2 years with this issue and not sure what to do.

Thank you

 

[j.w]

@BSTN
Sorry I have no idea's on this subject.

 

[Mmathis]

Hello and welcome!

Sorry, I can’t help you. Maybe contact a pool company for advice.

 

[zeuspaul]

I used Rapid Set mortar troweled on available at HD to seal a cement block reservoir. It works well and has held up over time. It sticks well to portland cement based products. It is stronger and shrinks a lot less. I don't know if it would stick to your existing coatings. It would probably best to remove them first but I don't know how you would do that short of sand blasting.

 

[brokensword]

this is what concrete/cement does; crack over time. Doesn't matter unless you need structural stability or a waterproof environment. You'd have to regularly fix as there is no flexibility. That's why EPDM and even HDRPE is used--they can handle what the earth does all around it. If your concrete pond can't move as a unit, it cracks trying. Not sure why a liner would be out of the question? Sure would be easier and a lot less stressful wondering when the pond will leak again. I'd add up the cost of trying to fix and the cost of a liner, then make a decision knowing the liner will be with you at least 20 years if not longer.

 

[GBBUDD]

I used Rapid Set mortar troweled on available at HD to seal a cement block reservoir. It works well and has held up over time. It sticks well to portland cement based products. It is stronger and shrinks a lot less. I don't know if it would stick to your existing coatings. It would probably best to remove them first but I don't know how you would do that short of sand blasting.

Problem is they have coated over the concrete so any further coats masonry coats will not bond .

I'm afraid the only reasonable option will be to install a liner over the whole thing