# [Wet Thumb Forum]-How far should I open the main valve on the CO2 cylinder?



## Jeremy S (Apr 9, 2006)

How far should I open the main valve on the CO2 cylinder?


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## Jeremy S (Apr 9, 2006)

How far should I open the main valve on the CO2 cylinder?


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## farm41 (Feb 1, 2003)

All the way open

Matt
If you're not making any mistakes, you're not doing anything


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## ekim (Jan 31, 2004)

dido


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## Guest (Mar 31, 2003)

Jeremy,

Your main valve should be open all the way and your regulator for smaller PSI levels should be kept at ~10psi.

At least that worked best in my situation.

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## Moe (Feb 1, 2003)

I run 20 psi on mine









Moe


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## Guest (Mar 31, 2003)

I guess 20 is fine too.

I alway looked on this as a simple reaction.

If you have gas coming from main tank with 20psi pressure you are putting more force on needle valve. Meaning that you have less room to "play around". Each twist is making big difference since there is 20psi behind valve. If you have only 10psi behind valve then you have less stress on the needle valve and more room to "play around".

This is just my plain understanding.









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## imported_Platy (Feb 4, 2003)

If you dont open the main all the way 99% of the time it will leak - even if its a small leak - it will leak.

ImaNewbie -
125 Gal - 3.07wpg - 99% flourite - Pressurized Co2 - Uv Sterilization when needed - Densly Planted


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## gsmollin (Feb 3, 2003)

Turn it back 1/4 turn away from the stop, so it doesn't get stuck.


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## Jeremy S (Apr 9, 2006)

Thanks for all your replies. I was just wondering because the directions for the m3 CO2 system say that you donât need to open I all the way only enough so it registers at 800 psi.


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## gsmollin (Feb 3, 2003)

I've seen that too, but you can't trust the tank valve to stay open. Its not designed to be a throttle, and has only two positions- open and closed. Some people who have opened it part way have had it re-close on them.


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