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Old 05-07-2006, 04:27 PM posted to
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Default Anyone with experience of pump cage?

With a sponge being used water flow ois reduced whicxh allows UVC
light to do a better job. Without spinge there is no restrictin so you
have higher water flow and too fast of flow with a UVC does not work
as well. Forget the sponge prefilter crap, use the cage, and put a
valve on the outlet to slow down the water flow.....unless you like to
clean a sponge.
In short, the water is flowing too fast for the UV to do its job

On Wed, 14 Jun 2006 22:56:23 +0000, Jan-I

Hi, new here, my first post and I'm looking for a bit of advice with
something we're unfamiliar with. We've had a 1000 gallon pond with
orfe, GF, etc since we moved here 9 years ago. We have a Blagdon pump
(operating waterfall and small fountain, filter box, and UV.

A couple of weeks ago our pump packed up, so we bought a new one direct
from Blagdon. It came with a free plastic "pump cage" which the pump
fits inside and is supposed to reduce maintenance. Our old pump slotted
inside a large square sponge filter, which caught lots of sludge and had
to be cleaned out weekly/fortnightly depending on the time of year.

We have not had very clear water yet this year (usually it's really
clear) and assume it's because the old pump wasn't working properly
before it packed up. We installed the new pump, put a new bulb in the
UV and thought we would be clear within days.

However about 5 days later, we are no clearer. There seems to be gunge
in a suspension in the water, which is not clearing. The filter box,
which hardly ever needed cleaning got so gunged up it pushed the lid
off and started leaking.

Is this a sort of run-in period for the pump with the cage? Does the
cage mean that the silt/waste etc is pumped into and trapped in the
filter box, instead of being trapped in the square sponge filter as it
was previously. Will the water, does anyone think, clear, or does
using the cage instead of the old sponge filter mean less maintenance,
but murkier water? Is the muck being pumped back into the pond at the
other end - is that why it's not clearing? If so, we still have the
option to ditch the cage and go back to using the sponge filter. But I
note that the newest Blagdon pumps (we bought an old model as it was
what we were familiar with) are actually encased in cages - I can't see
a new product giving an inferior performance as far as water clarity is
concerned - even if it does mean less cleaning.

I don't know whether to persevere longer (how long?) with the cage, or
revert to the sponge filter. I'd be grateful for advice from anyone
with similar experiences.

You can reach -Ed Alston at

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