"Elaine T" wrote in message
...
scs0 wrote:
My pond is made from an EPDM liner so concrete construction is not an
issue. I'm glad you asked about the tap water pH because I forgot to
mention that, I tested the pH last week and it was in the 7-8 range. I
forget what it was but it was something pretty typical like 7.2 or 7.4.
Over the weekend I finished up some work on the pond and filled it
with an additional ~400 gallons or so of water. This was a combination
of tap water and rainwater that poured on Saturday and I'm still having
problems.

I'm not sure what my sand's pH would be, I'm not right on the coast
but I suppose the entire peninsula was right on the coast at one time
or another. I would love to use clay soil. Up north I saw some native
ponds that had a clay bottom and the smooth heavy texture seemed
perfect for aquatic plants but I haven't been able to find clay
anywhere. I've tried big outlets like Lowes and Home Depot. I've
tried smaller nurseries, I tried two rock & gravel yards, and I've
tried water garden speciality places and nobody sells clay. I always
read about people using clay for aquatic plants but no one ever reveals
the secret on where to buy it! I'm afraid of using kitty litter
because I don't feel secure that its added perfumes and other additives
would be safe in a pond with plants and fish.

I tried an aquatic plant soil once, I think it was Scotts, and it was
horrible. I had expected it to be granular clay that would disolve
when wet, but the light chunks didn't dissolve at all. It was like
trying to pot an aquatic plant in styrofoam balls. The stuff was too
light and therefore had pitiful holding power. I can't believe its
still on the market.

Oh, and my pots aren't completely sand. I noticed that gravel always
seems to sink into the planting medium so since gravel makes an
adequate potting medium I mixed gravel into the pots. (It's probably a
75% sand to 25% gravel ratio though)

If you still have some pH Down, drop a few drops of it on your rocks, sand,
etc. You'll see bubbles as strong acid reacts with carbonate minerals if they
are going to dissolve and change your pH. It's an easier test than trying to
actually pH test a mineral.

I'm using Schultz Aquatic Plant Soil from Home Depot now. It's made from a
porous inert ceramic, and comes in fine gravel sized particles. I'm having no
problems with it holding down my plants - I even have some watercress rooting
in it. Maybe you'd like it better than Scotts.

I've had the same problem as you finding plain clay kitty liter. I can't find
anything that doesn't contain perfume or bacteriocides and they're all labeled
"not for garden use."

--
Elaine T __
http://eethomp.com/fish.html '__
rec.aquaria.* FAQ http://faq.thekrib.com

Kitty liter is mostly bentonite. You should be able to buy straight bentonite
at a suilding supply store like Lowes.