What's the best surface over concrete for a large indoor pond?

[BOBKAH]

I currently have a 5000 gal pond. I sealed it with black rubber ( HUGE MISTAKE). I somehow convinced my wife to let me build a 10K gal. pond in my basement. It will be concrete with windows....similar to my current pond. However, I do not want to use the rubber. Can I just keep in concrete? Should I try to cure the concrete differently? Can I put either fiberglass or gunnite? Any suggestions would be appreciated. Thanks

 

[pacu mom]

Research polyurea - it is used in potable water tanks, etc. Unfortunately, it is not a DIY material and has to be applied by a professional. If I was having a large tank built, I would use polyurea.

 

[ken31cay]

Pond Armor might be an option. I'm used it a few times to preserver larger pieces of driftwood but I believe it's made for sealing concrete ponds and wood tanks.

 

[jjohnwm]

Pond Armor works well on concrete, and I suspect that most of the other 2-part epoxy finishes would work as well.

I'm curious; what was it about the liquid rubber that you didn't like? I've never used the stuff but have toyed with the idea and found mostly good reviews on it. What happened with yours?

 

[BOBKAH]

I have used 2 different types of liquid rubber. I made sure to follow all the directions perfectly. The stuff still comes off over time. Lucky for me that it didn't cause any leak issues. About half of it is off and it's a pain to clean it out of the pond. My convicts gather it and bring it into the rocks. I have to watch my PH because of the concrete. There's worse problems to have. But, I just want to make sure I do it perfectly this time.

 

[Midwater]

I have found bare concrete ponds are excellent for water quality. The surface of the concrete itself seems have have some bio-filtration properties.