Important note: If you use the venturi on your powerhead, do not repeat not
use a flimsy soda bottle! The powehead is just powerful enough to partially
collapse it. I am too embarrassed to repeat my story again, so just trust
me and use a juice bottle.

The check valve will not prevent the powerhead from drawing CO2 from the
bottle. When you first start it up, there will be a lot of bubbles as the
venturi evacuates air from the bottle. This will actually accelerate the
transition from aerobic to anaerobic CO2 production (a good thing or, at
least, not a bad thing).

kush

SlimFlem wrote in message
news:5trR9.549947$WL3.147894@rwcrnsc54...
Question, I want to start some CO2 tomorrow so I am going to make 2 DIY
bottles for my 75. I saw on this site,
http://www.geocities.com/Heartland/H...37/index.html, that the airtube
can be stuck in a powerhead. It seems like since the "air port" on the
powerhead sucks air in, it would also suck from the CO2 bottle. Will the
check valve prevent this? I would like to do this, but need some more
experienced person to tell me about this method first.

thanks.

"Jim Miller" wrote in message
...
controlling the output by restricting the flow isn't a great idea for a
variety of reasons. you're better off adjusting the co2 concentration by
the
efficiency of your diffuser or perhaps the size of your bottle.

btw, adding too much yeast at the start will get production started at a
high level and depending on your brew and yeast type cause a quick fall
off
thereafter. yeast population will grow over time so adding too much at
the
start is a bit of a waste. use the minimum necessary to start co2
production
at a comfortable level.

jtm

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"SlimFlem" wrote in message
news:YHlR9.548545$P31.182441@rwcrnsc53...
What is the best way to control the output of bubbles on DIY units?
Don't
you need to watch your PH levels and adjust bubble flow? How would you
do
it with this type of setup?