Gunnite is just a dry spray on type of concrete. Concrete has as one of the
byproducts of the hydration reaction that makes it strong, calcium
hydroxide, saturated lime water. Calcium hydroxide has a high pH of about
12, which is too high for fish. The curing process for concrete is best
accomplished with plenty of water, which will improve the impermeability of
the concrete. Therefore, once the pond has been sprayed about a week, fill
the pond with water and let stand for 3 or 4 weeks, then remove all water
and allow to dry. This drying will allow carbon dioxide in the atmosphere
to react with the calcium hydroxide to make calcium carbonate, or just plain
limestone. Drying also allows the pores to get air inside, which inhibits
the movement of the lime within the concrete. Refill the pond and monitor
pH. If the pH starts to climb into the high 8's, then you can lower the pH
by using muratic acid, used for cleaning swimming pools. Over time, the pH
will stabilize, and the slow leaching of the concrete actually helps to
maintain better water than the liner.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


wrote in message
...
does anyone know if this would be harmful to fish?i've had such bad luck
with liners and i'm tired of fooling with it.since i can't build it
myself
using concrete,i'm thinking about having the swimming pool people blow
in the gunite stuff.
is it safe for fish?robin