Blueline making crackling noise

S

Spar

Premium Member
I have a blueline external pump, forgot the model but whichever is around 700gph with 3/4" input and output. It makes a crackling noise when running. Is this normal? The water input is 2" PVC for the first bit and then reduces to 1" for the last 1 foot before getting to the pump where it reduces to 3/4". The output is 1" PVC and goes 5 feet up.

Thoughts?


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The pump could be cavitating. How deep is the water level on the intake side? Try raising the level if you can.
 
3/4" is the inlet for the pump right? Can you tell if the noise is comeing from the pipe or the motor?
 
Dennis, the water line is about 4 feet high in the water storage container, the pump sits level with the base of the container.

Steve, yes 3/4" inlet, and 3/4" output. Good question on where the noise is coming from. I will have to get my ear next to it when I get home. Could it be the pipe vibrating? I think I recall holding the pipe still and the noise still being there, but not sure how much thought I put into it at that point.
 
I don't think it would be from the pipe vibrating. It either the motor or the pipe cavitating, but with 3/4 out and 1" in I think you should be ok. I did not hear anything though when we tested it. I would have thought it would have been cavitation then if it is now.
 
I will try to get a video with the sound on it posted. It is still pumping just fine at least. Just a little annoying, but since it is in my garage, oh well. But don't want to burn the pump out if that is a possibility.
 
I was playing around with this over the weekend, and when I restrict the input by slightly closing the ball valve the issue goes away. Why would the amount of water going to the input be an issue? So much quieter now!


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Couple things I can think of but totally a guess. The pressure from all the water is causing an issue. Since the tank is so tall and it's 200g, makes a little sense since it was not make noise when it was only 30g of water, But I would think aquarium pumps could handle that type of input pressure. Or you are starving it of more water at a constant rate. Where it's not starved for water then has a lot of water then starved again, the on off noise you may be hearing. Again both are just total guess and not sure I can buy either one of them.
 
@Spar wrote:
I was playing around with this over the weekend said:
You really should never resrict the input to a pump. It sounds more and more like cavitation, have you considered increasing the input pipe size? I only ask because the input diameter is listed above as both 3/4" and at 1".

Cheers,
Click to expand...
 
Unforunantly the way I set it up it reduces too quickly to 1", making me have to redo the entire plumbing. I tee off the bulkhead so that it can go to two pumps (one only runs once a day for a couple minutes, the other continuous). But would be a lot cheaper to redo it all than keep having to buy new pumps when they burn out from starved.

What if I were to just switch out the pump to say a Mag 9.5? It is 3/4" input as well, but is there a chance that Mag's will handle it differently?
 
You have 1" all the way up to the pump though right?
If the mag does not pump as much water then it would for sure handle it differently.
 
Correct, it is 1" all the way up to the pump. The Mag 9.5 would be a tad higher gph than the blueline I have. Would be worth trying out before buying all new plumbing over again.

I was following Marc's guide on Reef Addicts:
http://reefaddicts.com/content.php/283-Plumbing-Primer-how-to-do-it-correctly/view/2

He has pretty much the same pump as me (although he has 1" input/output) with the same gph (800), and he uses 1" for the last foot or two. Seems like my situation would be the same/similar to his.
 
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