I was told after it cures out, there is nothing toxic left. I looked at a couple of pond forums and asked a lot of questions before I built my pond. It had to be concrete because it supports a portion of a retaining wall. The only drawback is, it has to be done every 7 or so years. Mine s almost two years old and does not have any problems.

That is awesome! I killed one of my koi with sawdust from graces clubhouse :-(

You painted the entire pond interior with that stuff? If so, I am going home right now and do it (want to get out of this mad traffic).

Why do you need to paint it. We have an old concrete fish pond built same year as the house, 1926. Pond had a couple of cracks in it. Drained the pond, used hydraulic cement on the cracks and filled it back up. Put the fish right back in. This was 5 years ago. No problems.

Hey! I just signed up last night to sell my stalled project, after a 13 year absence :)
But this is my current area of expertise - I make/repair fountains and make art with water.
My go-to, bulletproof waterproofer for concrete substrates is DIY Wet Basement Waterproofing, Finishing & Flooring, Swimming Pool, Deck & Concrete Crack Repair, Roof & Industrial Floor Coating . It's the real (fairly expensive) deal. If you properly install this stuff, your pond will not leak unless a faultline opens up under your back yard . Given your shading and the fact that it's underwater, you shouldn't need to topcoat (UV exposure can cause color to change).

This was my immediate thought when I read your post and I'm surprised it took this long to be posted. The only problem is locating the crack(s). If they are obvious, simply open them a bit with the tip of an old can opener and trowel in the cement. If the cracks are small, hair-line, and all over the surface, then the paint over suggestions are probably the best for now.

Dryloc in hand. Will report back soon

Get cheap goldfish and toss them in there. You'd be amazed what they will live through....

If not, my kid will kill em'.

get a few nice ones

they breed like rabbits

I got ten feeder goldfish in the spring
they grew from an inch or 2 too 6'' now
and have spawned 4 times in less then 6 months

I now have near a 100 plus 10 koi

+1 on drylock

I am excited for my kids. Thanks for the support on the Drylok.