If you can find the cracks you could try enlarging then and refilling the
crack with a sand cement motar with a water proofing additive added then
when dry you could reseal the whole pond with a good pond sealer (after
first giving the concreate a good clean)

Jon

"Scass" wrote in message
...
Hi folks

This is my first time posting here. I'm just wondering what advice you
would all have in this situation.

I live in Tokyo, Japan, on the ground floor of what they call a
"mansion", but what you would call a condo. It's about 40 years old. The
original owner was into koi, and built an approx. 50ft x 10ft pond along
one side of the building. It's within a yard of our back door step!
(Quite a unique setting in urban Japan!)

The pond is stocked with koi and some kind of goldfish, about 30
altogether.

Now, this pond is about 40 years old. The water level, until recently,
was obviously lower than original, but relatively stable. Suddenly, a
month ago, the water level started dropping suddenly and we now have to
add 4-6" of fresh water a day.

After 40 years, the inner concrete surface is not particularly clean. It
has lots of surface roughness and small cracks, but no obvious large one
that has just opened up.

Although the pond is part of the "common" area of the building, most
people here are not very interested in spending money on repairs -- why
would they, if they live on the upper floors! So it looks as if I and a
couple of others will be stuck with the bill -- if we decide to repair.

So, my questions are (1) what would be the best approach to repairing a
pond like this and (2) how likely is it that I would be successful
without specialist equipment?

--

Steve