Water flowing up my CO2 diffuser

[Yoemen]

I have a Red Sea 500 CO2 diffuser, I noticed that I was having issues getting the CO2 tornado to form in the diffuser. I was looking at my tubing and with having my CO2 bottles under my tank the Water was flowing up the tubing from my diffuser. So I moved my bottles up on top of my lid and the CO2 is flowing fine, but I didn't think water flowing up the tubing would be a problem....

Is there anything else I can do? I am using bulkhead fittings to connect my bottles to my tubing and when I made the switch to bulkheads from just running tubing through the bottle cap and that is when I started noticing the issue.

 

[cichlidkeeper91]

Get a water stopper that you can put on the tubing so it only make co2 go through the tube and water cant.

 

[Yoemen]

I have check

I have check valves on it, but the water just comes back up the tubing all the way to the check valve.

Also, I have used the bulk heads because people said they would make a better seal, but it seems I am having more trouble keeping it air tight with the bulkheads then I did just using silicone to seal around the tubing