I have this pump. It is an Iwaki md40rlxt. I know that its not made to operate with any pressure. I have it backed off about a quarter turn and the ball valve coming out of the pump (return side). Will this be ok? Does anyone else do this? I am getting too many micro bubbles in my new 100g tank with 1 single 1" built in overflow. It has the Ken Stockman modified stand pipe. I have tried everything to help the little bubbles in the tank but decreasing the flow is the only thing that "somewhat" helps. Thanx for any info!
Dennis

Moved to Tanks, Filtration & Basic Equipment forum.

Id like to know too... is it better to place to control valve after the return outlet, or before the inlet???

Great Reefer Man: IMO that shouldn't be a problem. I have my LG4 backed off about 1/4 of the way as well and have no problems with it over-working the pump. I've also read that turning down the pump outlet is just like having it work against a higher head pressure. As long as you don't turn it down to the point of it max head you should be okay.

CnT: You should always restrict a pump on its outlet side, never on its inlet.

Thanks fdm...

Im constantly learning new stuffs on tis BB.

FDM,

You say never to restrict the inlet on a pump. I will be using a LG4 or IW4 (havent decided yet) in a closed loop.
It will be sitting under the tank and a pipe will be running from the top of the tank to the inlet. Will this be ok? Is this restricting the inlet flow? I was told by LFS that it would be ok.

Kashi,

This should be fine as long as the water in the inlet side is primed with water. You can just put some plastic tubing on a powerhead and pump some water into the inlet pipe to prime it. As long as you keep the pump's impellar submerged and the inlet pipe filled you will be fine.

Frank