Any of the concrete sealants will require the pond be thoroughly cleaned.
The algae on the side will prevent bond of the sealant to the concrete. A
good sealant is ThoroSeal. It is a cement based sealant that is painted
onto the surface. Use the acrylic bonding/waterproofing additive Acryl 60
with it for extra waterproofing and better durability. I would mix it thick
and trowel it onto the surface to give a smoother finish than what you
describe is currently there. That will give some additional thickness that
will help it bridge any fine cracks that are causing leaks. Because it is a
cement based product if there are moving cracks, it will crack. An
alternate sealant is a liquid neoprene type sealant like Herco H55 from
AquaticEco. This would be more flexible, and therefore less likely to
crack, but it is very expensive.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"Larry D. Gibbs" wrote in message
news:PEcwa.833099$L1.242015@sccrnsc02...
I have a Concrete pond that was here when I bought the house about ten
years
ago and the water level goes down rather fast. I see that who ever built
the
pond applied some sort of sealant on the bottom of the pond "off whitish
color" and the water seems to stay at that level. I have heard of G4
Sealant
but don't know where to buy it and how expensive it is. The pond is not
smooth, it looks like a rake and shoe imprint were used. What kind of
sealant can be used and also where can it be bought. I live in Tacoma
Washington. I had goldfish in it and they survived until the raccoons got
them.

Thanks,

--

Larry D. Gibbs

http://www.larrygibbs.com/
Only left handed people are in their right mind.