If your going to hve a reef tank you dont want air bubbles in the main tank anyway as they can collect on the coral tissue and cause major problems. In addition some fish can be irratated by a large amount of air bubbles. I have a PBT that I have had for at least 3 years now and the only time it had ICH or what resembled ICH was when my sump pump was injecting microbubbles into the display tank.
The adjustment of the seaclone has nothing to do with the MJ powerhead. Just like the maxijet the seaclone uses a ventri to inject the air. This venturi though is not a part of the PH
or at least it wasnt in the seaclone I used to use. One of the issues with a ventri design is the adjustments can be extremly sensitive.