UV/Chiller loop question

[schmuttis]

We have 3 pumps that process our 120 gallon tank.

1 draws from the 2 overflows in our main tank through the sump/refugium and back to the tank - Blueline 55.

The second is just a closed loop within the tank - Blueline 40.

The third - Blueline 30 (and this is which we have a question about how to process) is though the chiller and UV. We had this loop initially take from the first sump stage and discharge into the third sump stage. We are getting a lot of air bubbles in the tank with this configuration. Prior to adding this third loop we did not have this problem with air bubbles in the tank. Yesterday we put a small sock on the output pipe to hopefully diminish the air bubbles in the main tank but we still have them. Another thing to mention is that the chiller and UV are in the crawl space below the living room (essentially a 1/2 floor below).

I was thinking about taking the one overflow from the main tank into the UV/chiller loop and discharge this into the first sump stage. I'm not sure if this could cause other problems. My questions are:

Are there any problems with processing non-mechanical filtered water through the UV filter and chiller?

If I only draw from the first stage sump and also return to the same stage sump would this cause a problem with the chiller and main tank temperature?

The way our tank is set up the water is taken from the 2 side over-flows and is returned from the 3 stage sump to 4 jets in the main tank - 2 on each side.

[bertoni]

I would draw and return from the first sump stage, personally. I don't think the unfiltered water would cause a problem, though.