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Discussion Starter #1
I have a small 5 gallon Spec V tank, and have a 5lb CO2 tank and a Milwaukee regulator. I have a Fluval diffuser attached to the set-up via CO2-proof tubing with a check valve.

My issue is that, when I get the right bubble count (about 1 every 10 seconds) for the tank, when I turn the solenoid off and back on the next day, CO2 never comes out of the diffuser without me having to up the CO2, which causes gas to come out of the diffuser almost immediately, then adjust it back down to the desired level.

I can't figure out why it won't come out on its own without daily manual adjustment.

I've thought it might be a leak in the tubing, or not enough initial pressure because I only want 1 bubble every 10 seconds maybe? The odd thing is, the bubbles keep coming out of the regulator, yet the diffuser never releases gas.

Maybe a leak after all?
 

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Hey, that is a very easy fix. Simply increase the working pressure of the regulator by turning the big knob on the regulator's body:icon_cool
 

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I get the right bubble count (about 1 every 10 seconds) for the tank, when I turn the solenoid off and back on the next day, CO2 never comes out of the diffuser without me having to up the CO2, which causes gas to come out of the diffuser almost immediately, then adjust it back down to the desired level.
I think the key factor is that you want a very low bubble count ( 1 per 10sec is veeery low. Normally most people measure in bubbles per second - generally about 1-3 bps.)

You need a higher pressure to start the diffuser flow than to maintain it. This extra breakthrough pressure is required because the diffuser pores are initially full of water and high pressure is required to open up the pores. Once the pores have been purged of water lower pressure is needed to maintain air flow across the diffuser disk.

That said - how do you go about setting the ultra low rate (and conserving CO2)? I am afraid the only option is to use a interval timer on your CO2 solenoid. You can set it to run CO2 for one minute then off for 10 minutes. this way you can achieve the same result.

If any one else has any other suggestions.....
 

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Discussion Starter #6
Thanks for your replies!

I am actually only using the big knob on the regulator because Milwaukee said only use the needle valve if I absolutely had to in their instructions. Perhaps I need to adjust both to get 30lbs of pressure on the needle valve and see what that does. Think that'll work?

1-3 bubbles per second basically turns my aquarium into a giant bubble curtain. They get everywhere and the pH goes low fast. It's only 5 gallons and honestly, 1 every 10 seconds or so is all that's needed.

Would an in-line diffuser be better? Or do they use the same ceramic material that has tiny pores?
 

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Maybe put the regulator on timer and have it turn on 2 hours before the light on. That way it has enough time to build the gas pressure and put out of the diffuser. 1 bubble per 10s will take a little long for pressure.
 

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As some already said it can take a long time to build pressure after it is lost. This gets even worse when the line from the bubble counter to the air stone is really long.

Have you considered leaving it on 24/7?
 

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Discussion Starter #12
Would leaving it on 24/7 be ok? I've always worried about CO2 at night, but if it doesn't negatively affect the plants/fish, I would be fine with it.

I know plants don't need CO2 and actually need O2 during the night.
 

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Discussion Starter #14
I adjusted the big knob and the needle valve until the second gauge read 30 PSI and had about 1 bubble every 6 seconds, which seemed to work great. I let the system turn itself on the next day and whaddya know, an hour later bubbles came out!

Thanks everyone!
 

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I had the exact same problem, same set up, 5lb tank Milwaukee regulator w/solenoid.

As everyone else has said, I fixed It by increasing the working pressure. I ended up at 40 Psi. Works perfect now at about 2-3 Bbs.

Also your bubble count is really low. most people start around 1 Bbs and work their way up till their drop checker indicates a good concentration of Co2. How are you monitoring your Co2 levels?
 
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