When is the last time the bio balls in the down draft tower were cleaned or changed out? Check you air intake elbow and how is you pump output driving the skimmer?
bio balls are 3 weeks old, and entire skimmer was just cleaned 1 week ago, and its sitting in 8" of water. and i cleaned the pump also, pump is rated a 700gpm
one day it works like its supposed to and then it wont do a thing for a few days.
I have been running some type of etss/beckett since they first came out
and i see the same mistake being made all the time.
Make sure the water level is below the neck i prefer it at least a inch below it.
Leave it alone it is suppose to strip your water of protein then shut off that
how they work the more food and toc that are added the more it will skim.
Dont clean this skimmer it works better dirty if you clean the skimmer just wipe
the neck with a paper towel they dont need cleaning like a NW.
After cleaning the pump and skimmer it may not run at all for a week.
I go 6 month without cleaning the neck of my etss 1000 thats why you have a collection container.