# Diffuser filling with water



## Donjalex2 (Nov 24, 2013)

I have my C02 canister above the aquarium thinking that it would keep C02 in the diffuser when I turn it off, but in the morning the diffuser completely fills up. Then when I open the valve that I've calibrated the night before it doesn't move an C02 until I open the adjustment nozzle more. Any suggestions?


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## Donjalex2 (Nov 24, 2013)

Thank you for the reply. I'm using a plastic ADA check valve, but I guess it's not working. Understand the water needs to be in there, but when it's working about 1/4 is filled with C02 and I was hoping that it wouldn't completely fill with water after I turn it off at night. When it does completely fill up I have to readjust/recalibrate the valves every morning. Is this normal?


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## C2C (Apr 7, 2009)

I would have this happen more often during the winter than the summer. I think because of the colder air there is not enough back pressure to keep the water out. (I had a brass check valve from GLA) To fix it if it got too full I would turn it upside down out of the water with the co2 on and it would get pushed out no problem. It would still work perfectly eventhough there was a lot of water inside. Now I use the Fluval ceramic diffusers. I dont have that problem anymore and cleaning the disks is so much easier.


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## Donjalex2 (Nov 24, 2013)

Thank you C2C. What diffusers by Fluval do you have?


Best Regards,

Don
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## dmagerl (Feb 2, 2010)

Are you using pressurized CO2 or DIY? 

If pressurized, whats the output pressure setting of your regulator?


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## DarkCobra (Jun 22, 2004)

It's harder to push water through the tiny holes in the diffuser than CO2.

It can take some time. If you only waited a few minutes, wait longer.

If after a half hour it's still not operating, you may need to raise the pressure on your regulator (and turn the needle valve down correspondingly). This will help push the water out.

The reason this happens is because when the CO2 is off, water continues absorbing what CO2 is left. This creates a vacuum, which sucks water back into the system. Given enough time, it travels back into the diffuser, then the line.

This happens regardless of whether you have a check valve, or the quality of it. The valve is only there to make sure water cannot travel past it and get to your needle valve and regulator, which would eventually ruin them.

While a better quality check valve will stay open a little longer once you turn off CO2 for the night, letting more CO2 pass and delaying the process a bit, this is not really a problem with your check valve. Even with the best check valve in the world, if your CO2 remains off for longer than usual for any reason, the diffuser will still fill with water. Better to address it by setting a proper pressure that will allow the diffuser to resume operating within a reasonable time under any circumstances.


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## Donjalex2 (Nov 24, 2013)

Thank you everybody for the replies learned a lot from all the responses really appreciate it


Best Regards,

Don
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