Just got the 125 today for my 75g mixed reef
Seachem Aquavitro 125. A few notes on how I set up and tune the skimmer.
Do NOT put the air intake/silencer on the skimmer overflow. It will take in water and not drain (like when I turn off my pump to do a water change). I hang it outside the sump.
Having the skimmer between the min level line on the pump and the top of the pump seems to work best (6-8 Inches).
I let the pump take as much water as it can. I took the restriction pin out of the water intake. (this is one thing I did not mess around with, might be able to use if you have sitting deeper in sump)
Put on the collection cup.
I set the air to full close and the overflow all the way down. Crack open the air line and watch the bubbles. Too much air and I get big air bubbles in the neck. I like lost of little bubbles, so my is set mostly closed and this give lots of small bubbles up in the neck of the collection cup.
Then slowly bring up the overflow until the bubbles are at the top of neck of the collection cup.
1/4 turn adjustments (at most) I tweaked it to work best for me. Took a few tries to get it right where I wanted it.
I tried having in deeper water, but my skim was very wet and filled up quickly, could not keep the head pressure down.
You don't need the filter & sock on the overflow, but it does a good job of keeping the noise down.
