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Re: CO2 rant

> As for its fish killing ability, this is actually attributed to
> regulator more so than the diffusor.  Some people report that when the
> CO2 tank gets low the regulator losses its ability to regulate the flow
> of CO2 and the CO2 tank dumps all of the CO2 into the fish tank
> resulting in a pH crash.

FWIW, I just ran my gas tank to nothing and had no problems with the MMM
needle valves(I have 6 on a manifold) I had no variation or any flux in the
pH all the way down. There's about 30+ feet of CO2 tubing as well. I use the
cheap Dave Gomberg regulator, no check valves etc silicone tubing and my own
CO2 reactors. Got about 10 months or so out of a 10 lb tank on 5 plant
tanks(one valve is for a terrarium to kill off pest) and some 520 watts of
lighting relative to the CO2 and the CO2 flow was left "on" 24/7 but the CO2
reactors are turned off at night. Flow rate was the same as well.  All the
tanks are monitored by a pH pinpoint monitor. Variation of the norm were
seen in both instances(+,- about .1 to .15 pH units).

>  Unfortunately no diffusor, reactor or
> injection into a filtering device that I know of can prevent this
> dumping, because it is a failure of the regulator.  There are two ways
> around this phenomenon:

Apples and Oranges analogy.
Only the glass style diffuser require the high pressure though. Cannot
compare them therefore to others unless you add a needle valve in which case
you have solved the issue right there.

> 1) Don't let the pressure in the CO2 tank get too low.
> 2) Put a needle valve downstream of the regulator.  This does not
> prevent dumping but it does aid the regulator by providing back pressure
> and by controlling the dumping to a preset limit.  Thus your pH may drop
> but not as far as it would without the needle valve.

See above. I've never had a pH crash using a valve even when I let the tank
get low.

> I have a regulator - needle valve - Eheim diffusor setup running and I
> have let my CO2 tank pressure goto zero without any dumping phenomenon.
> I found that the PSI drop with the needle valve was greatly reduced in
> speed.

I would suggest another brand of glass diffusers if you enjoy that method.
The all glass ones sold by Monolith are nice and much better IMO than the
Ehiem's. Good for smaller tanks and such. Use a needle valve and you'll be

Tom Barr