Micro Bubbles ???

[Steelhead]

I have an overflow rated for a 75 gallon tank and a Cap 220 return pump. I have been running flexable hose for my return (untill this weekend). My skimmer sits in my sump. My return pump is located in the last chamber of the sump. The water from the return and skimmer has to go thru the chaeto and three baffles before it hits the return again. I have even put a sponge over the last baffle to kill any potential bubbles. I can not see any bubbles in the chamber that holds the return pump. I thought maybe I had a leak in the flexi hose so I decided this weekend to plumb the return with hard pvc. everything turned out great. I was very diligent when I made each connection. plenty of cement. Zero Leakage.
I still have micro bubbles. Not huge amounts, but enough that I can see them consistantly. I cleaned the return pump about a week ago. I didnt see anything that could cause bubbles inside the pump. The impeller blades looked ok to me. This pump is at least 3 to 4 years old. The id of the pvc is 1/2in the id of the flex hose was 3/4in. I thought potentially by restricting the flow this would make a differance; it didnt.
Can you guys help me out. What the heck am I overlooking??

[ckusnierek]

Any powerheads in the tank?
Right now my Tunzes have a lil algea frowing on them and shoot out bubble about every 5 mins...

[beyondpostal]

possiblethat the skimmer is leting micro bubbles out the tube that returns the water to the sump. try adjusting the skimmer. min did the same thing and i adjusted theneedle valve and that fixed the micro bubbles.but it seems like i have to adjust the needle valve every couple of days so it could be that the pump for the skimmer might need to be changed.

Bill

[grallster]

It doesn't sound possible that the bubbles are coming from the sump with all those barriers. Are there still microbubbles in the tank when you turn off the return pump?

[Steelhead]

I do have two power heads in the tank. They are new within 3 months. that doesnt mean there not dirty though. I honestly cant say if the bubbles go away when the return is off. I will check tonight. I will also shut the power heads off seperately.