"rasta" wrote in message
news
thought i would draw on the collective wisdom of this group.

i have a 300g inground pond with a 45 mil liner that has been running
since april of this year. it has a 950g/hr mag pump with the discharge
split into a venturi and a bioforce 1000 bio-mechanical filter. it has
been home to 6 - 5 inch comets during this time with no probs. been
doing 10% wcs monthly and did a 20% wc 3 weeks ago when i cleaned the
filter pads (rinsing the pads in water taken from pond for the wc). i

Adding a bag of freshly activated carbon to the mix probably sucked all your
oxygen out of the water, you need to pre-soak this stuff b4 use. Do you have
a waterfall? Hows your surface agitation? Your water parameters sound fine
(how old are your test kits?) so oxygen depletion is the only thing that
springs to mind.
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**So long, and thanks for all the fish!**