"Nikki Casali" wrote in message
...
Dick wrote:

It is my observation that filters are actually "strainers." They hold
the larger solids, but the water passing by is eroding the solids and
letting the stuff to return to the tank. Oh, woe is me, I predict
disaster due to negligence.

Well, I just discovered why one of my external filters' flow rate dropped
to almost nothing, even though it apparently looked clean. It was driving
me nuts. I hadn't cleaned the prefilter sponge for almost 8 months, but it
looked pristine. I scrunched it in a bucket full of water, just in case I
was missing something. What did I then see at the bottom of that bucket?
Masses of white snail shells. Over the months, tiny snails had got through
the strainer then bred and died, finally choking the sponge with their
insoluble remains. The flow rate after that was incredible. I'd forgotten
how much water it could shift when it was new.

Nikki


A common snail tactic unfortunately.
the old clogging of filter parts with their dead.
I once had an otto 450G cannister impellor jammed after a power outtage for
5hours on masses of dead floating tiny snails.
When the impellor finally worked it's way free it pumped the nastiest
ammonia filled goop into me tank.
Oh did it smell.
To it's credit, the fluidised sand bed filter on it's side (rainbow or
something) had converted most the ammonia to nitrite by morning but still
dam I lost some fish!!! 6X2X2 african display. One of several tanks but was
a few buckets of fish gone :-(
hated snails with a vengence..... but then after the ocky I find them
really quite interesting.
still lucky you had the prefilter on! clean that more often and you can
clean the actual filter much less.