I have a new toilet downstairs in the basement (below grade about 6ft) The toilet flushes very good, water pressure good, however when you first flush the toilet a 2 inch air bubble comes up after that no problems. Never a problem otherwise.

Any suggestions would be appreciated

I have a new toilet downstairs in the basement (below grade about 6ft) The toilet flushes very good, water pressure good, however when you first flush the toilet a 2 inch air bubble comes up after that no problems. never a problem otherwise.

Any suggestions would be appreciated

You have a partial clog in the drainage line that services the toilet. Let me explain what's happening. You flush the john, The discharge bangs into the partial clog in the line and starts to rebound back pushing a bubble of air ahead of it. This is what you see in the toilet. Then, because it's not completely blocked the discharge drains away before anything overflows. This can only get worse. The drainage line that services the toilet needs to be snaked out or if you're on a septic tank it should be checked to see if it needs to be pumped. Good luck, Tom