Help! Tank full of air bubbles
I have a 40 gallon breeder tank that has been set up since May. I bought a PS2 filter system that had a hang on the back box and a canister filter with built in skimmer in the cabinet under the tank. I constantly had issues with flow and air bubbles. I moved over the summer and had a guy babysit my tank at his house. He is the former owner of a local aquarium store and did a good job. He recommended that I get rid of the hang on the back box. He had built a system that he would sell me and install at a reasonable price. $75 and I wouldn't have to change out the canister filter part. So he installs this and it works fine for about a month then once again air bubbles. He comes over and disassembles all my filtration trying to find a block. Nothing. He goes off to think about it and it has been working fine for about a week then last night more air bubbles. Today it is horrible. I love my tank but all these issues with the filter are driving me crazy. With this said here are my questions.
1. Will the bubbles hurt my fish or coral?
2. Should I continue to let the guy work on it-it's a pain to get it scheduled.
3. Can I just get a canister for the back of the tank at Walmart and it work?
4. Do I need a skimmer etc. I have about 60lb of live rock in the tank.
Any recommendations/advice is appreciated. I just want to enjoy my tank and not have a constant battle with air bubbles.
Thanks and Happy Thanksgiving!