I've been asked to quote for glassing the inside of a concrete structure that they want to turn into a fish pond. I haven't seen the actual structure yet but it was originally some form of water tank (they're quite common out here in Portugal) so I'm not sure it will actually need any fibreglass, maybe just a coat or two of resin to seal it a bit better, unless it is actually cracked in places. I'll have to try and get a look at it over the weekend. It might turn out to be very weak and I need to basically make a complete fibreglass pond within it.

Aparently there is a surface area of 14square meters to glass (sides and bottom), which if my maths are right means it around 5 cubic meters holding 5000 liters of water.

So 2 questions:
1. If it can just be resin coated or skinned with 1 or 2 layers of glass, will polyester bond to concrete or will it have to be epoxy?

2. If it needs a complete pond built in it any ideas on what sort of lay up it would need. In this case I guess I would go with polyester. Never used it before so now might be the time to try it?