Air in the DI Mystery

[rdelong]

OK folks. I need some help with an air entrainment mystery. I have a 5 stage RO/DI unit supplying a trash can with a float valve and the RO/DI has an auto shutoff valve installed. I'm using a 150 GPD membrane for the first time (used a 75 for years in this set-up#. When I make water using this set-up #I get great quality water out of the RO by the way#, I slowly build-up air in the outer #inlet side) of the canister. I take about 35 gallons of production to generate enough air to displace all of the water outside the DI cartridge. I don't have any leaks anywhere when the filter pressurizes after the float valve shuts off. I just baffled to determine the source of the air and eliminate it without having to vent the DI cartridge every time. Any ideas?? Thanks in advance.

http://reefcentral.com/gallery/data/500/9031IMG00077.jpg

[AZDesertRat]

Thats normal. DI cartridges flow up through the center not around the outside so what you see is normal. The higher the level of your output line the higher the level in the canister and the lower the level the lower it will be, they all do it. It does not affect water quality or production.

[rdelong]

I certainly agree about the flowpath but where is the air coming from and why didn't I see this buildup previously?

[AZDesertRat]

There really is no air its just the path from the DI has little resistance. Raise the DI outlet up over your head and you wil lsee the canister fill up. No biggie.

[rdelong]

I gotcha it's coming in thu the outlet tubing as the cartridge drains. Thanks