Throttling back a MAG

[Reefland]

I know there are a lot of people that reduce their pumps output by putting a ball valve on the output line; but from what I read it is usually with people using Dolphins or Iwakis.

I plan to use a MAG and want to get an 18 to make sure I got enough flow but if it is too much, has anyone every experienced problems from throttling one back? It's got to be harder on the pump so how can I expect a MAG to hold up if I need to hold some flow back?

Thanks,
Scott Z.

[golfish]

It shouldn't be a problem

[Reefland]

I was thinking of T'ing the return into 2 or 3 lines forcing current in different directions. I could go with a Sea-Swirl or 2 but their additional equipment that takes additional funds. I figure a MAG 18 @ 4' head with split 3 times should be plenty for the size tank I am planning.

Scott Z.

[scubadude]

I would not be afraid to throttle back any pump as long as you have some flow going through it and its on the output side....I say GO for it there is so much more versatility when you can throttle your current. I think T'ing off can be a little tricky but if you oversize your piping a size or two then you wont have as much problems with head reduction....and of course you know the drill scott...elbows, sweeps, and flex tubing. Did you ever get your tank? If you still want me to build one for you I can....just let me know. Heres is a 120 im working on now for a buddy of mine.

[Reefland]

Hey Rocky!

No I don't have anything yet. Don't be surprised if you get an e-mail. I have been unable to locate anything locally to date.

Scott Z.

[stang69]

Scott

I have a mag 12 and have a ball alve on the output side. I am just using it a little but I have had zero problems thus far. (knock on Wood)


Jeff

[silverstar]

Hi , I found a chart at www.superskimer.com that has a chart so you could get the right size pump for the size tank you have or going to get.

[stang69]

add one m to that it will work hehehhe


Jeff

[FZ1Lawman]

I am a Mechanical Engineer and I agree that all valves shoud be on the outlet of the pump. Not too many people know this (except Mechanical guys) that throttling a valve down on the outlet to reduce flow actually decreases pump energy used. Think of it this way.... If you ran your pump and throttled the valve closed, the pump does very little work(less energy-electricity) You see, the pump only needs to overcome the "head pressure" from the valve down to the pump. So, the pump is not esposed to the "system head pressure". The impeller just sits there spinning with very little Head pressue.

Here's the teade off though. If a pump is throttled doen too much, the pump will "cavitate". The impeller just starts spinning and doing no work ie less energy. However, if a pump cavitates for a long period of time,, the impeller will waer out very quickly because of air and banging of water on the impeller. You can hear it cavitate, the impeller is just spinning freely and not pumping anything. So, if one wants to throttle down a pump as much as possible, turn the valve completely closed and slowly open up the valve until you hear the noise in the pump go away. This will be your minamin flow rate. If it's still too much, you will need to buy a smaller pump. "Cavatating a pump for severa; hours will not permanently damage the pump as long as you have the throttling\shut-off valve on the outletof the pump.

Still don't believe it? For you doubters out there.., take an amp probe reading when the pump is pumping at the maxamin then throttle back on the valxe and you will see the amperage drop dramaticaly.