~ jan wrote:

Are you hoping for a clear water pond? Koi mud ponds use clay for good
growth of the koi, but the water is usually murky brownish green. Koi &
even goldfish fish love to dig in clay for the aquatic critters that live
in it. Thus you can rarely see them. Now if you're just going to grow
lilies or something... ? What are your plans for filtration?

12x12, you'd be better off with a rubber liner if you want clear water.

Yes, I want clear water. I was unaware that bentonite would make the
water murky. I suspected it might, but was not sure. I wasn't planning
on koi or goldfish, but perhaps some kind of small fish that we could
catch and eat, and plants, too. There will be the usual filtration
setup. If I can have clear water with tilapia, crappie and minnows, or
something like that, and still use bentonite, and if bentonite is
considerably less expensive than a rubber liner, I'd still like to use
it. What do you think?