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Re: [APD] Re: Needle Valve / Metering Valve for CO2

On Fri, 18 Feb 2005, James Purchase wrote:

Aquabotanic sells a 4Plex Manifold which apparently has built-in needle valves. Could this be used down-stream from a higher quality metering valve to distribute CO2 to multiple aquariums? Or would I need separate metering valves for each additional aquarium?

I don't think there's much point in having a high-quality metering valve upstream and lower-quality downstream. If anything, it's the reverse that's true in my experience. Actually, I don't have any valves upstream, just a regulator, going to a manifold, and then spread out to multiple needle valves (high quality or otherwise). It's important that each needle valve have a certain amount of forward-pressure from the tank, otherwise most or all of the gas will tend to take the easiest route out, i.e., the least backpressure.

An analogy here would be air pumps. If you have a big reducing valve that then splits into two not-so-well controlled "gang valves", one finds all the bubbles going into one tank only, unless the airstones are exactly matched, their level of sumergedness the same, etc. On the other hand, it's very easy to tap lots of valves directly off a high pressure pump like they do at the stores.

Hopefully someone else who's used the AB manifold will chime in on whether they're high enough quality. Gotta be better than the ARO NO1's I'm still using from 8 years ago, though!

- Erik

Erik Olson
erik at thekrib dot com
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