Big D, the tank looks great as always. The 300 is only going to have two pump's, so i'd just get the msx250 when it comes out. It'll be plenty for a 180 or 300g tank.
A Sea K, i replied to bunkerbean a while ago but should have posted it here. Yes, i'm very happy with the results the msx200 is showing, its pulling 2 cups a day of the nasty nog. Its still holding steady at 45-50scfh, but you do have to realize that air # is coming from a rma series air meter, which will restrict the air at the top so i need to get a new meter to see what the actual air pull is.
As for the recirc pulling in air bubbles coming down from the bp and body. Thats not a concern at all. There are no micro's escaping below the bubble plate and even if a few were getting sucked in to the pump it wouldn't make a difference at all.
When i said it took a while for me to get it right i should have explained it more. The way the input of the pump goes into the bp is at a bit of an angle. When i recirc'd it, i went straight in. I should have went at an angle. It just took a long time to line it up correctly, thats all. After it was lined up, no problem. HTH