New Member, Bubbles from Pump?

[magnetic1]

Hello all, new member here. I actually met dbartco tonight through another friend!

 

Hey dbartco! Nice meeting you.

 

Anyhow, off to my question. Ive got a Mag 9.5 return pump. The water level is WAY above the inlet, yet it shoots out microbubbles every 10-15 seconds or so. Does anyone know why it is doing this or how to prevent?

 

When I used to run my Rio2500, it would only do this when the water level in the sump got low... and I'd just refill more water and it'd go away. But right now, the water level in the sump is WELL above the Mag.

 

Im stumped! Any help is appreciated!

[ReefMon]

Try sticking a PVC 90 ell on the intake of the pump, this will prevent the pump from sucking air from the surface.

 

HTH

Glenn

[Guest tgallo]

sounds like pump cavitation.

 

 

Suction Cavitation occurs when the pump suction is under a low pressure/high vacuum condition where the liquid turns into a vapor at the eye of the pump impeller. This vapor is carried over to the discharge side of the pump where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure. This imploding action occurs violently and attacks the face of the impeller. An impeller that has been operating under a suction cavitation condition has large chunks of material removed from its face causing premature failure of the pump.

 

 

Suction Cavitation occurs when the Net Positive Suction Head Available to the pump is less than what is Required ------------ NPSHA < NPSHR.

 

 

 

Symptoms

 

1. The pump sounds like it is pumping rocks!

 

2. High Vacuum reading on suction line

 

3. Low discharge pressure/High flow

 

Causes

 

1. Clogged suction pipe

 

2. Suction line too long

 

3. Suction line diameter too small

 

4. Suction lift too high

 

5. Valve on Suction Line only partially open

 

Remedies

 

1. Remove debris from suction line

 

2. Move pump closer to source tank/sump

 

3. Increase suction line diameter

 

4. Decrease suction lift requirement

 

5. Install larger pump running slower which will decrease the Net Positive Suction Head Required by the pump(NPSHR)

 

6. Increase discharge pressure

 

7. Fully open Suction line valve

[magnetic1]

Thanks for the input so far...

 

Right now, the input end is just an open filter (no sponge). THe outlet goes straight up from the mag pump to a 1/2" Sea Swirl. So 3/4" output to a 1/2" Sea Swirl. So I'd think the discharge pressure is greater?

 

The pump is silent and not making any abnormal noises.

 

Also, occasionally the SeaSwirl causes a "whirlpool" effect. Is the only way to remedy this to extend the outlet lower into the water?