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Re: [APD] Re: Bubbles? -- or - Can sumpin' be a gas?

Interesting conversation. Your comment on starvation of O2 in the filter itself is precisely what I worried about, it would just make a big reactor and no bio filtration. However, my understanding is CO2 and O2 have hardly an relation in water. The amount of dissolved CO2 is not related to dissolved O2. Assuming good aeration during the overflow (very likely with all the turbulence), there should be enough O2 to support a colony of bacteria in the filter.

Going back to my reactor, I've posted another picture here:
So everyone can see the design (and flaw). You can see the sump bin at the bottom-right. The air enters the tubing after the pump output through a tap I made using a garden irrigation system part. The flow goes right-to-left, then up the reactor, with the bubble of CO2 :-( This caused it not to trap from, what would be, down flow of water. I ended up with much larger bubbles in my tank then I had before by just placing the CO2 output near the impeller of my sump pump.

Questions (assume I've reversed flow):
-Is the reactor tall enough (I'd say it's ~12-14" tall)?
-Is there enough media to sufficiently break apart bubbles (there are more bio balls in the elbows)
-How do I reduce the reverse pressure of the pump->airline->regulator?

-Dave T.

Andrew Mitchell wrote:
On Wed, 2004-02-04 at 02:35, S. Hieber wrote:

Depending on how it's done, it seems that a Trickle filter
will not, or at least need not, cause all the CO2 to
escape. While my experience was an increase in CO2 use of
about double, George Booth has reported results much

In George's article where he reports his experiments, he notes that a
10lb bottle would last about 5 months in his 90 gallon tank.
I did some calculations on what this worked out as a couple of years
ago, but I can't remember the exact results! I think it was well over 1
bubble/sec (of the size of bubble that I use), which would still be much
higher losses than you suffer from. Perhaps your cannister method was
just extremely efficient?

Looking at David's figures of similar CO2 usage in a tank half your
size, and third the (increase from 2ppm in) CO2 level, his losses are
about 5 times your losses. Perhaps he should consider sealing his sump a
little better and/or boosting his carbon with Seachem's Flourish Excell.

Uncovered, I'd expect a trickle chamber to shed almost all
the CO2 -- or a goodly amount anyhow.  Covered, this should
not be the case -- where's it gonna go? In fact, a covered

I've read/heard that there can be a large loss in the overflow itself,
which increases the partial pressure of CO2 in the overflows (and
perhaps between the water and the lids). Whilst I use a method (which I
will write up some day) that virtually eliminates this particular issue,
it might cause problems for some people. In this case though, I agree
it's the filter.

trickle should be a good place to put your CO2 line, using
the wet/dry chamber as a CO2 reactor, no? I haven't tried
this but I don't see how it would be diff than a smaller
external reactor loaded with bioballs.

Has anyone tried this?

I have tried it, briefly. My early results were inconclusive... my sump
is not perfectly sealed and I was worried that the positive CO2 pressure
may eliminate too much O2 pressure from the sump, suffocating bacteria.
Sure th water would then leek O2 into the sump, but how much if the sump
is pressurized?
My other concern of a well-sealed sump  was that in the event of a power
failure the water level would rise faster in the sump (due to the
trapped air) and spill. I am particularly careful about avoiding spills
(no external reactor for me!) as last time we had a spill (diswasher
leaked, under 100 litres we believe) the insurance company had to pay
$10,000 to replace the damaged section of floor. They would not be
impressed by a repeat performance! Hence I refuse to seal that part of
my sump. (yes, my sump does have an overflow to the garden, but not
quite fast enough)

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