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Re:Hang on filters and CO2

Kudzu wrote:
> I was at Steve's web site and saw a photo of a "hang on the back filter"
> with a piece of plastic(?) attached to the spillway. [snip]
> Will this keep the surface agitation down
> enough to keep from loosing the CO2? Steve is this a piece of plexiglass or
> some sort of ridged plastic? Anyone have any other idea's?

This is just a piece of overhead transparency plastic glued on with
silicone. It seems to work if you judge by the fruits of my labours. ;-)

I found that the polyester fibre filters in these box filters clogs up
fairly quickly and then you get spillage out the inlet side which
quickly drops the CO2 content sufficiently to create a steady rise of pH
by decalcification (use of carbonates in the tank for DIC). I had to
keep rinsing these things out every week and they are not easy to clean. 

Alternative:   A few months back I switched to sponge type filters on
the inlet of my powerheads. These things also plug up in about two weeks
but they are very easy to clean. Even when they plug up, I don't notice
much difference in CO2 dissolving rates because I use the VENTURI inlet
on the output side of the powerhead with a length of 1/2" hose about 8"
long. This design works well with yeast or bottled CO2. Sorry but I
don't have a picture of this filter on the web site yet.

Another friend who has powerheads without the venturi aeration port put
a tap into the hose and attached his CO2 there. We have been observing
the effectiveness of this and it does NOT seem to be a good design. I
think the venturi is very, very important if you are not running the CO2
through the inlet of the pump. The venturi creates a stream of very fast
moving water with a negative pressure (relative to atmosphere) which is
how it is able to draw air in when used as an aeration device. He's
going back to injecting CO2 into the pump inlet. (read on)

Another SERIOUS failure mode which I have seen on 4 separate occasions
involves feeding a yeast CO2 line into the inlet of a powerhead through
a filter device. When the inlet filter plugs, it develops a strong
negative pressure on the CO2 line and this is sufficient to collapse
plastic yeast vessels and draw the deadly sugar/yeast mixture straight
into the aquarium! BEWARE! After the second occurrence of this, my
friend threw away his yeast bottles and purchased several ARO valves and
CO2 cylinders since this is cheaper than replacing fish and plants. He
uses three way adapters to connect several needle valves onto each CO2
cylinder and can handle several tanks this way.

Steve Pushak                          teban at powersonic_bc.anti-spam.ca 

Visit "Steve's Aquatic Page"            http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!

Aquatic Gardeners Association     -                  technical advisor