Can you avoid rocks entirely? They are hard to clean. Could you let the
plant roots do the filtering and then just drain or vacuum out the muck
rather than have rocks to provide surface for the bacteria?

Might make life a lot easier.

The rocks, themselves, will become algae covered and look the same as river
rock: dark. Bill is right about the buffering they provide.

Good luck.

Jim

--
____________________________________________
See our pond at: home.bellsouth.net\p\pwp-jameshurley
Ask me about Jog-A-Thon fundraiser (clears $120+ per child) at: jogathon.net

"Pam Gibbs" wrote in message
...
Lowes didn't have river rock so DS brought home marble chips, which is
white
and pretty, for the veggie filter. Is it OK to use marble in the veggie
filter or is it bad. Someplace I read it will lower make the water too
alkaline? I feel fairly sure that the rocks won't stay pretty and white
for very long, too. Thanks for any advice!