I'm going to link this to the SPS thread since that's what I deal with mainly. I recently upgraded my Tunze 6100 to a 6200, WOW that's worth the money!!! I now have a problem with the pump pulling in air from 8 inches below the surface of the water! It makes a tornado during high pulse which it pulls down further and further until it pulses a air shot..........I'm assuming this is OK since it's not a ton of air? I would hate to burn out this EXPENSIVE pump but I think the air is only getting to the impelller and not the shaft so I assume there should be no issue. I'll just wait for a reply here. Thanks........my Ph should be great this way 