last pump question

reefrandy · #1 12/13/2007, 10:17 PM

for today that is, a pump that is pressure rated should be used for a filter like an ocean clear but can you use it for a cl or fuge return, i know thet have a smaller out side orfice but if you go from that to a larger diam whats the diff? i can see not using a non pressure pump for a filter but what about hte opposite . I hope this isn't confusing. you pump gurus please chime in thx randy

oct2274 · #2 12/13/2007, 10:26 PM

you can use a pressure rated pump for a closed loop or return just fine. running larger plumbing will give you better flow then you would get with smaller plumbing. Typically pressure rated pumps run at much higher wattages then flow rated pumps at the same gph. If you don't mind paying the electricity then it is fine to run a pressure rated pump in a non-pressure application. Also alot of pressure rated pumps should not be valved down if they flow to much for your application. This can actually hurt pressure rated pumps. On pumps that are flow rated like sequence darts it is fine to valve down the output. Also typically pressure rated pumps are quite a bit louder then flow rated pumps. Is that what you were looking for?

reefrandy · #3 12/13/2007, 10:33 PM

yes thanks ! i may change the housing(lilgiant mdx) to the flow housing of the non functioning pump depending on how quiet it is

AZDesertRat · #4 12/14/2007, 09:42 AM

Valving down a pressure rated pump actually help the pump not hurts it. By adding head you are duplicating a higher pressure situation thus bringing it into its best efficiency point on the pump curve. It will probably lower the wattage requirement, make the pump run quieter and cooler.

nmbeg · #5 01/11/2008, 03:11 AM

What does valving down mean? Is it simply using a ball valve on the output line (from my Dart) and closing the valve part-way?

I have a 125 gallon setup with a 50-gallon sump/refugium and I am having a terrible time with bubbles... I think part of the problem is just too much flow in the sump so I wanted to "valve down."

Thanks

AZDesertRat · #6 01/11/2008, 07:51 AM

Yep, thats it. Always restrict the discharge side and never the suction side though.