Koi Forum • Tiles as a pond lining??????????????? : Koi Talk
Don’t have to, I’m typing as fast as I can!
If you are referring to the 1 inch (ish) ceramic or the three quarter inch (ish) glass tiles, I don’t see any reason why they won’t be ok. Both tiles are inert so they won’t do anything significant to the water. The correct grout to use is cement based. I would suggest one of the Ardurite tile adhesive range, I’ve never had any trouble with those.
Being cement based there will be a small degree of leaching into the water, but this will not harm the fish and will add carbonate which will have a (tiny) buffering effect.
A tiled swimming pool isn’t water proof just because it’s tiled. Ceramic or glass tiles obviously are but not the grout in between them. All proper swimming pool builders render the pool shell with two coats of water-proof render before tiling to make the pool waterproof, then the tiles are just for the aesthetic look.
Two things to note. First check that the cement waterproofing additive is fish safe, I don’t think that would be a problem but check with the manufacturer just to be sure. Second, you can’t just slap the second waterproof coat on top of the first. The first is waterproof so the second coat wont stick unless you provide plenty of “keying” for it to grip onto. This is easy enough when you know what you are doing, just make sure the guy has done it before or it will fall off again.