I top up my pond. I change about 1/3 each year. I have a veggie filter drags
"stuff" out of the pond. After 8 (9?) years I can still see folds in the liner at
the bottom of the pond (4'). My koi stir up any sediment and the pump gets it into
the veggie filter and I remove the mulm with a shop vac. My pond is netted and there
really arent a lot of trees nearby to dump leaves etc into the pond.
I have nice lake water, but there is chlorine/chloramine and I am not thrilled with
having to put sodium thiosulfate into the pond. My fish are healthy. Ingrid

On Sun, 13 Apr 2008 17:17:47 EDT, Joan wrote:
Do you really have to do partial water changes in ponds if the water
chemistry is okay? My pond is probably about 1500- 2000 gallons, only
about 12 goldies, pH solid at aroun 8.5, alkalinity around 100, no
ammonia or nitrite, lots of plants, a good waterfall, a nice
mechanical/bio filter.
Do I really have to drain the pond every few years for a major
cleaning, or can I just scoop the gunk up off the bottom with a net?