U-Tube for my overflow keeps accumulating bubbles.

Relying on an aqua lifter pump is a very bad way to remedy the situation. If you have an overflow that needs one, that just shows that the engineer who designed it didn't really know what he/she was doing, as the velocity of water through the overflow is too slow to keep it cleared of air. A properly engineered overflow will be self-clearing (of trapped air). The eShopps u-tube overflow is a very, very well-designed overflow system. All the OP needs to do is to increase the flow from the return pump, and the problem will go away and never return. Speaking from experience.

 

Thank you guys for all of your help. I ended up buying 1/2" vinyl tubing from home depot. Instead of using the one 1" Eshopps utube, i just zip tied two of the 1/2" vinyl tubes together, and so far its been a few days with no bubble accumulation. But is it possible that the overall GPH has slowed down?

With the Eshopps 1" utube, the water level inside the surface skimmer box, would always be lower than the DT's water level. So the water would flow down into the skimmer box to be siphoned to the back. But now with the two 1/2" tubes, the water level inside the skimmer box is about the same as the DT. Could this mean that the GPH has significantly lowered? Any ideas?

Because of this, the surace of my water is not as clean as when the water would flow down into the box, than siphoned out the back.

 

Get rid of the DIY tubes and put the 1" tube back on it. You were given the best solution by the previous responders - simply increase the amout of flow from the return to the DT and your issue will go away.

 

The pump is set at max, and the ball valve is wide open too. Is my next option just to get a more powerful pump?

 

Hmm, that's probably the answer, what size pump do you have now? You will want the next size up or maybe 2. You want to be able to dial the flow down slightly with the ball valve in order to reach the right equilibrium between the tank and the sump so it pulls the micro bubbles all the way through the U-tube instead of trapping them at the top.