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re: CO2 Liquid Discharge Into Tank

Steve Turner described a collaping yeast CO2 bottle. A friend of ours
here in Vancouver had that happen twice. He was feeding the line into
the water inlet of the powerhead and had a micron filter cartridge
attached to it. He had serious fish deaths with this. The second time he
removed all the fish, plants and changed the water. Major hassle. It
happens when the inlet filter gets plugged and the inlet develops a
higher vacuum.

He got the design from another friend of ours here in Vancouver who has
modified his system to prevent this. He uses a very long plastic tube
from the outlet of the bottle. The bottle is placed on the floor and the
tube routed up to the ceiling and back down to the powerhead in the
tank. This means the powerhead has to develop about 7 or 8 feet of
vacuum head in order to lift the yeast water through the loop and this
is enough to prevent disasters.

I use an alternate way; the CO2 feed goes into a venturi on the outlet
of the powerhead. If the inlet gets plugged (as it inevitably will if
you ignore cleaning), the flow rate drops and the result is less rather
than more vacuum. Since I use a CO2 bottle, regulator and needle valve,
the CO2 input doesn't change but the reactor becomes less efficient as
the flow rate goes down.

I have used hang on type box filters to reduce the amount of turbidity
from floating gunk. The plants and fish are happy without mechanical (or
biological) filtration but I'm not especially when I want to take
pictures. The box filter (Whisper type) will also get plugged by mulm
after about a week and the result is a waterfall effect as the water
spills over the inlet side of the box. This causes a big reduction in
CO2 levels and a resultant pH increase over time. Don't neglect
maintenance, eh.

I find the weekly cleanings of the Whisper filter tiresome, so I'm
trying to use a sponge filter on the powerhead inlet to catch the mulm
and prevent the powerhead itself from plugging as quickly. There's a
small grill on the inlet that gets plugged with gunk. I have one that
works well for several weeks now but a smaller sponge I got from
Aquarium Services just won't fit. Local Vancouverites might try Matt's
aquarium on Hastings where I got the large sponge and adapter. I don't
know why more powerhead sponge filters aren't made. I guess the new
fashion is powering a sponge filter with an air pump.

Aquatic Gardeners Association