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Re: [APD] Diatom filter and Haze (CO2 loss)

I think the more likely mechanism, unless this is what you
meant, is that as the media in a Vortex filter clogs, the
vapor pressure in the filter jar, after the media, lowers
and gases come out more easily. This because the Vortex
sucks water through the media, into the pump, and out into
the aquarium. So there is a slight lowering of pressure on
the pump side of the media. Even without CO2 added to the
aquarium, you can see the Vortex tend to develop "gas" as
it becomes clog, the same as happens with an Eheim canister
filter where the pump is after the media in the flow path.
There isn't any increase in pressure on the intake side of
the media as the media clogs -- as the media clogs, the
Vortex pump is less able to move water and less able to
maintain a pressure on the intake side of the media. If the
Vortex used a postive displacement pump instead of a
centrifugal pump, the behavior might be a bit diff.

Otoh, the System One pushes water from the pump, which
actually sits inside the aquarium below the waterline,
through the media and out into the aquarium.

Scott H.

--- Pete <peteal at sympatico_ca> wrote:

> You can remove large quantities of CO2 from your tank
> using a diatom filter if you are removing lots of
> contaminants, that goes for a Vortex filter with the
> output below the water line. Basically once the diatom
> gets well used and starts clogging up, the back pressure
> forces the CO2 out of the water (and maybe O2 for that
> matter).  Can be very visible and shows as lots of
> bubbles forming on the outside of the filter.  Once while
> filtering a tank which had a green water bloom, I had a
> PH spike from 6.2 to 7.4 (which is my basic tap water PH)
> in an couple of hours.  First the diatom powder had
> gotten nice a green and then I noticed bubbles forming on
> the filter also, but it didn't sink in until I saw some
> of the fish coming to the surface to skim the water
> breathing.  Did a check and found the large PH change. 
> Stopped filtering, raised my spray bar from the canister
> filter above water level for some aeration.  To avoid the
> problem you probably could just stop and replace the !
>  diatoms in the filter once they get clogged.
> Pete.
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> Aquatic-Plants at actwin_com
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