Why all the bubbles?

[rcpalmer1]

Quick background. I had two systems. One had been running for 10+ years and one for two. The new system had a much better filtration system than to old one. So I connected the two systems into the one sump and add a line coming off the manifold. Both tanks are supplied off the same return pump. The protein skimmer has been off for weeks.

Now I have bubbles in the old tank. I have shut off water flow to the tank. All powerheads are well below the surface yet there are thousands of micro bubbles. The tank is bare bottom. When I redid the tank 3 weeks ago I removed the rock but kept in a container of saltwater. I cut some of the rocks in half. All of the new cut side have already been mostly covered with coriline algae. I was think they would stop but I can't tell where they are coming from or how to stop them.

 

[reef lover]

got some pics so we can see the plumbing and bubbles?

 

[cracker]

reef lover is correct. we need to see both tanks & how they are connected. Thanks !
Also how big is each tank?

 

[rcpalmer1]

You ask so here are both tanks and plumbing. I don't believe it can be the plumbing because I can shut of the return pump. So there is no water entering or leaving the tank for an hour and there are still bubnles. It has to be caused by the powerheads or something with the rocks the best I can figure.

Main tank is 120gallon

Small tank is 56 gallons.

Both returns run into the same sump.

Both tanks all supply lines come off one manifold.