Sump pump cavitating like crazy! Help Please...

[drewread]

the only check valve I have is after the first T that goes to my ca reactor or is used for water changes...

:roll:

 

[Anonymous]

Podman'

Cavatation will occure whenever the absolute pressure in a line reaches the vapor pressure of water (or any other liquid). Essentially, the pump is pulling harder than the intake flow allows and the water is mechanically, "pulled" apart, leaving water vapor to fill the space.
So, if drewread has cavatation, then he must balance his input and output in some way. Either that or his use of the term "cavatation" is wrong and he has an air leak which will also cause bubbles.
As for my "credentials", I have a BS in Mechanical Engineering, Industrial Engineering, some MS time, 35 years in the metals industry in jobs from production engineer to COO.
What are your "credentials"?

 

[Mac1]

As for my "credentials", I have a BS in Mechanical Engineering, Industrial Engineering, some MS time, 35 years in the metals industry in jobs from production engineer to COO.
What are your "credentials"?

Bah! What's that Worth

Joking aside, I do have to say I find this thread very interesting. I'm in the process of setting up a new tank, and will be getting into some pretty powerful external pumps. Since this is the first time I won't be plumbing w/ all submersible pumps, and will be tripling the flow I'm used to having in my sump... I know this is an issue I'll have to deal with. I'll be real curious to hear how it turns out.

- Mac

 

[Anonymous]

drewread,

do you have any of that spongy bubble arrestor stuff?

if so use it to grab some of that air coming out of the skimmer.
if there are bubbles in the water, that is possibly the cause. if they can gather somewhere prior to the pump housing and make a slug of air, that would be a definate cause.

 

[cal91666]

drewread what was the outcome of this?? please post and share. thanks

 

[drewread]

So far there has been no real outcome... I have been on vacation for a week with my pump restricted... and am back now.. I will hopefully be rebuilding my sumps baffles tomorrow in the hopes of having a larger area near my sump outlet open for the pump to suck water from and to have some more baffles in order to force out more air bubbles before that chamber...

I will post more when I am done...

Thanks again all!

 

[drewread]

Well... this evening I removed the two closest baffles in the picture from the site address above. My belief was that there was not enough water available to the sump outlet... however:

There has been no noticeable improvment in the cavitation noise that the pump is making...

Any more ideas...

The updated pictures are posted at:

http://www.andrewread.com/PersonalPages/plumbing.html

 

[caecosystems]

I am a zookeeper at the Houston zoo. I am in charge of the 4,000 gallon reef tank there. I learned from the senior aquarist there, George Brandy, that longer intake runs decrease the intake cavitation pressure. Try increasing the length of plumbing going from sump to pump.

 

[caecosystems]

I am a zookeeper at the Houston zoo. I am in charge of the 4,000 gallon reef tank there. I learned from the senior aquarist there, George Brandy, that longer intake runs decrease the intake cavitation pressure. Try increasing the length of plumbing going from sump to pump.

 

[seahawkjohnny]

I would either put a sponge block in the area where tha water leaves the sump, and if you can point the skimmer return up stream from the return pump...this will give you some added time for the bubbles to dissipate, also your pump is pretty powerfull for your tank volume 3600 gpm for a 90 gal tank...thats 40x an hour, when tha water is going that fast, it will produce more bubbles since the water is crashing more, and it gives the bubbles less time to work themselves out

 

[MarkO1]

cwa is right regarding the cavitation. If you are in fact experiencing cavitation (which I believe you are based on your ability to eliminate it when the valves are partially closed), then you need to try to reduce the sucking forces on the intake side of the pump. A larger diameter hose could help. eliminate all fittings too.
Have you tried submersing the pump directly in the sump without any intake fittings?
_________________
Rehab information

 

[seahawkjohnny]

cwa is right regarding the cavitation. If you are in fact experiencing cavitation (which I believe you are based on your ability to eliminate it when the valves are partially closed), then you need to try to reduce the sucking forces on the intake side of the pump. A larger diameter hose could help. eliminate all fittings too.
Have you tried submersing the pump directly in the sump without any intake fittings?

hey Mark.....I used to live in Lowell, I lived close to University Ave. thats when I was a college student....

 

[drewread]

I see that some of you have browsed my main site as well... Unfortunatley all the pictures there are of my old tank (90 gallon).

I now have a 130 gallon main tank...!! Much nicer for the fish to swim in...! It has been up for just less than a year now... I have been really busy starting up some businesses as of late and have not updated my site due to time but I will try to update the site this week.

If you were going to ask, this problem has been happening since I started the new tank... ;c) I have tried the pump in sump thing but will try it again now that I have removed some baffles...

This is a great resource..!

 

[caecosystems]

Did you try to lengthen plumbing? Maybe combination of increaseing pipe diameter and lengthening. I totally think that pump is so strong with a short and small diameter intake plumbing that it is causing spontaneous cavitation (pulling the air out of the water). To show you an example; take a 1" diameter clear, flexible hose and gravity siphon water from an empty aquarium (nothing but tap-water in it) into a bucket, like the way you would do a water change. When the water is traveling nice and fast in the hose, make the hose suction end contact the bottom glass quickly. All of a sudden, bubbles where there were no bubbles. Spontaneous cavitation......and they say length and girth don't matter. 8O ..... :roll:

 

[drewread]

Yes I understand how cavitation works (from boating actually) but it doesn't explain that it occured with a number of other pumps of varying strengths...

Besides, the pump comes with 1" fittings so I would assume that these would be adequate. Am I wrong in assuming this?

 

[Anonymous]

How is your pump mounted in relation to your sump. Is it a straight line into the pump and does it change elevation? I believe you are having cavatition, or reducing the outlet would not help. Please explain how your pump is hooked up or post a picture. Otherwise we are just guessing and its a waste of time.

 

[drewread]

there is a picture link at the top of this thread... but here it is again.

http://www.andrewread.com/PersonalPages/plumbing.html

 

[Anonymous]

Drewread,

You said......... "Unfortunatley all the pictures there are of my old tank (90 gallon)."

I thought that maybe something had changed. Your picture shows a very short and efficient inlet. If you don't have an air leak, then your pump(s) may be too large. If you are pushing little or no head with a high output pump then you will cavitate. The input size on the pump is designed for a certain flow at a given head range. If this pump was designed to run at a much higher head, it will outstrip the input. If you want to move a certain volume at a certain head, you need to size the pump for both the volumn and head. You just can't use the most powerful pump with a 1" inlet and expect it to fit all applications. You may need a low pressure pump with a 2" inlet to do what you want. You need to decide your parameters and then pick the pump.
Sorry, but that's the way I see it.
That is also one of the reasons Reef Central has a head loss calculator. To help aquarists decide on pipe size, flow and pump parameters. Try it and see if it helps you decide what's wrong.

 

[MarkO1]

Seahawkjohnny, I went to UML too, actually lived right off Univ. Ave as well (corner of Gershom and Sarah Aves). Small world, huh?

But since I'm such a stickler, cavitation doesn't actually "pull the air out of the water", in reality what it is doing is pulling the water apart. The bubbles you see (or hear the effects of) is the water changing state. From liquid form into vapor (gas)form. Water boils at different temperatures at different pressures. So in theory, if the pressure is low enough, water would boil at room (or tank) temperature. The cavitation is occuring because the suction of the pump is so strong that it is allowing the water to boil at your tank temp.
This does seem odd, that a manufacturer would design a pump to cavitate... I'm thinking the pump may just be defective.
_________________
Honda CB500T

 

[caecosystems]

MarkO,
I was just using laymen's terms, or perhaps you could say....searching for the words. Thanks for elaborating. The manufacturer maybe does not intend you to run the intake side 3"-4" from the water source. Again, I would try to lengthen the run, maybe not diameter....but lengthen it.