Skimmer not skimming??

Hi my tank has been up and running fine for nearly 2years,
The skimmer was producing brown scum a lot and I had to clean collection cup 2-3 times a week!
But for some reason in the past month there is no scum??
It's working just the same, bubbles reaching collection cup but they are clear and produce no scum?

Should I be worried?
Also skimmer pumping lots of bubbles into main tank via return pumps.

Is there anything I can add to aid skimming???

Advice very welcome.

Ps all params are ok.

 

When was the last time you cleaned the pump?

 

Maybe an adjustment issue?

 

I have found that with dosing of certain foods or ammino acids the foam production was greatly decreased. First though I would check the air intake and the clean the pump but not the canister or cup.

 

Hi it's a brand new pump the last one broke and I replaced it?

 

Is it the same model pump? Lower flow = fewer bubbles = less skimmate maybe air adjustment.

 

Does the amount of foam produced at the skimmer's neck equals the amount of foam produced originally when it was working good?

Mine gave me some problems a bit back, but the bubbles were bigger/heavier. Meaning it wasn't producing micro-bubbles..... just bubbles. I ran the pump/venturi combo in some water with vinegar and it helped clean the calcification from the venturi. The pump worked great for another week, until I started having the same problem.

My last resort was muriatic acid. I filled up a 10 gallon tank with 4 inches of water and added a little acid. Ran the pump in it for about 2 hours and it came out looking brand new. The venturi completely unclogged and this skimmer was rocking like in the old days!

 

coudl it be MFG oils on the new pump? if it the bubbles are reaching the cup and stacking up, it shoudl be fine.

 

if the pump is new isnt it going through the break in period?