running skimmer cup with no cap

salt life

Active Member
Hey everyone had a quick question,
I was reading on another forum that some skimmers are made with vent holes and other people just take the cap off of their skimmer collection cup. They were saying they do it because it helps with back pressure and it allows for for skimmate. I have an ASM-G1 skimmer and it doesn't have vent holes or anything like they were saying, I was wondering if anyone does run it without the cap and is there actually any effect?
TIA, I apreciate the advice.
 

dmv

Member
Skimmate can be some nasty smelling stuff if your going to run with out a cap be prepared with some ventilation just a thought ,
 

stdreb27

Active Member
Some do it for specific skimmers as a mod. I don't, one because my foam will bubble over and the cap keeps it in its place.
 

snakeblitz33

Well-Known Member
Interesting question.
The purpose of the vent holes in other models is to allow for air to escape once the bubbles popped. If the top is covered too tightly, air has to go somewhere, so it is backed up in the skimmer, decreases the water level, and shares an outlet on the output pipe of the skimmer.
With no skimmer cap at all, ventilation can occur, however, most protein skimmers have a cap with an inside cylander of acrylic which turns the bubbles downward into the skimmer cup. Without a cap, you could risk the bubbles building up really high and floating off. Also, without a cap, when the bubbles pop, nasty skimmate will fly everywhere, making everything smell. Also, an added benefit of having a skimmer cup - it keeps the smell down to a minimum.
If you check out "Volcano Skimmers" by Spazz, he makes a custom top which vent holes that contain a carbon lid that keeps the smell down.
IF you think about it, what if the bubbles overflow the cup, and make the side of your skimmer a nasty skimmate coated mess?
 
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