Restricting pump flow harmful?

firebirdude

User and Abuser
Can partially closing a valve on the pump return line from the sump cause damage to the pump itself? Its a Rio 1700. I wouldn't think so, because A) the pump is submersed in water so the cooling is taken care of and B) it's actually just like having some extra 90 degree elbows in line. Just increases head pressure.

I'm not asking if this is the best idea or anything. Obviously it's undesirable. My overflow can handle the max flow of the 1700, but it's very loud. I don't even need that much flow through my sump, so I dialed the flow back a bit and it's 1000 times more quite.
 

Playa-1

In Memoriam
It should be fine and that's a common practice. You could also just tee off the return line and use the excess water volume to drive media reactors. Keep an eye on the temp and make sure the pump doesn't run too hot. A little restriction should not be an issue at all but a larger restriction may cause problems with heat.
 

submersible

New member
Far from an expert, but I would think it would shorten the life span of the pump, as would excessive head, 90's, and other restrictions. A tee with a valve would be less restrictive.
 

goochesfish

New member
On certain pumps like the dart reeflo, decreasing flow coming out of the pump will increase lifespan of the pump. The only downside is that you're paying for extra pump for nothing. Probably better to buy a lower rated pump. My pump is T'd off to the chiller and phosphate reactor
 

nikon187

New member
I would say it depends on the pump. Most I would think would be fine but high pressure pumps like blueline may have some problems if restricted too much. I have always been told not to throtle back a blueline more than 20%.
 

evsalty

hmmmmmm
I would say it depends on the pump. Most I would think would be fine but high pressure pumps like blueline may have some problems if restricted too much. I have always been told not to throtle back a blueline more than 20%.

My mag 24 died an early death for that reason as well. Infact it ran hot as well due to the extra head pressure.
 

lordofthereef

One reef to rule them all
I would look up rio 1700 reviews or even ask the manufacturer. If in doubt, just put a small hole in the return line so that it is partially just dumping back into the sump. You can also plumb it this way, but a hole or a series of them is the quick and dirty way.
 

rcorbitt

New member
Check with the manufacturer, but a control valve on the output side of the pump is usually ok. I'm not a fan of holes in hoses, as invariably the hole finds a way to squirt water OUT of the sump ...
 

lordofthereef

One reef to rule them all
Check with the manufacturer, but a control valve on the output side of the pump is usually ok. I'm not a fan of holes in hoses, as invariably the hole finds a way to squirt water OUT of the sump ...

I agree but that is why it is quick and dirty ;)

If the hole is under the water line it usually never is an issue. Also, you can always reroute some of the water. In this case, many way to skin a cat :)
 

Patrick12

Crypt Assassin
It is a cetrifugal pump and not a positive displacement pump so that helps as far as your concern goes. But, if throttled too much it can be harmful. A little back pressure is actually good for the pump.....it is really all about the amount of backpressure you are providing. 20% or less sounds like a good guideline to go by. Have you tried to make a durso for your overflow to limit gurgling? You are also comsuming more electricity using a throttled and oversized pump....if that is at all of any concern. You might be able to find a smaller pump from a fellow reefer and cut back for cheap to nothing.
 

dots

Premium Member
I want to clarify it's throttling the discharge you are considering, should not be the intake.

As counter intuitive as it sounds, power consumption goes down as far as input, however mechanical and pumping effeciency goes down. All of these trends are related to the affinity laws. Exessive head can cause radial thrusting on the impeller wearing bearings, shafts, and seals prematurly. That may only be compounded from the heat produced from decrease in mechanical effecency

I am glad to see the correct advice as to the amount of restriction suggested and that it is not "optimal" but is an option as in situations like this where the pump is too large, a situation that should be avoided in the first place. All too often it is played down when one "wrenches down on it"

I would consider using the extra flow and pass it through a reactor or two tee'd off the return.
 
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firebirdude

User and Abuser
Thanks for all your responses. I have a standpipe for the overflow. And I figured the 6 90s on the return would cut a lot of the flow down, but it really surprised when I fired it up for the first time. Honestly, I would say I AM restricting it more than 20% with the valve alone. For this reason, I think I'm going to buy a smaller pump. These are cheap, so I'm just going to buy new. Not a huge deal. :)

Oh and I had thought about adding a reactor, but I don't have room for it inside the stand. So it would be the only, ugly, thing outside the stand. lol
 

insane

New member
When you buy a Rio new, they come with an accessory valve for restricting the flow of the output. Reducing the output of a pump actually reduces the wattage of electricity used. Only do this on a pump output and never restrict the intake as that can damage a pump.

The one that is not circled is a flow diverter.
rio.jpg
 
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