# Simple question about how the arrows on check valves should be pointing



## Darkblade48 (Jan 4, 2008)

HybridHerp said:


> However, with an inline bubble counter, should the check valve above the bubble counter also point up or should it point down (not sure if it pointing down would make it so that the contents of the bubble counter do not escape the bubble counter nor get a back flow of water into them accidentally.


The check valve should point in the direction of the gas flow. Using your reference points, you want the check valve arrow to be pointing "up."



HybridHerp said:


> As it is now, I have both of my plastic check valves pointing in the same direction, but this has caused the bubble counter on one of my tanks to pretty much empty itself, and has caused the bubble counter on my other tank to have both mineral oil and water in it.


Where did the water in the bubble counter go in your first aquarium? For your other bubble counter, the issue could be poor (cheap) check valves. In addition, if you are using plastic check valves, CO2 eventually makes the plastic brittle, and will render them ineffective.


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## keithy (Jun 8, 2010)

I think you're doing the right thing. I cannot speak for inline bubble counter, but my JBJ style bubble counter empties itself every other week or so. I don't think there is anything wrong, just need to refill it with distilled water every time. I don't use mineral oil for the fear that it would make a mess in my tank by accident.


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## Yankee (Jan 12, 2013)

Take your check valve and blow in it. You want the end that allows air to flow to go into your tank (otherwise you'll just block all gas from getting to your tank. The idea of a check valve is to only let things flow one way.


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