air bubbles in closed loop and scwd output

[georgeortiz]

I have put in two seperate closed loops into my 110 setup. I

have modeled my scwd setup much like the standard ones I have seen posted and I have also made a seperate closed loop manifold like the one that was posted a while back in Reefcentral as calfo illustrated.

To the point. I have air bubbles that come out with the water output. Is there a way I can eliminate the air bubbles. Would it make a difference that I am using DIY flare nozzles instead of round pvc outlets.

BTW if anyone is interested I can start a thread on how to make the flare nozzles out of standard pvc.

[NaCl_H2O]

What pumps are you using for your closed loops, and what size PVC from the tank to pump/inlet?

[georgeortiz]

I am using two mag 5's and 1/2" pvc with 3/4" adapters for the scwd.

[NaCl_H2O]

I had a similar setup originally on my closed loops and finally convinced myself that the MAG pump impellers were cavetating(sp?).

If possible, lower the elevation of the pump to a level below the tank, thus increasing the head pressure on the intake side of the pump. If they are cavetating, that should reduce/stop the cavetation. If so, the solution is to relocate your pumps, or replace the pumps. I didn't have the option to lower my pumps, so I replaced the MAGs with Blueline pumps. I also tried to increase the inlet pipe diameter, which helped a little, but didn't cure the problem completely.

There is also a chance you have an air leak along the pipe? Turn off the pump for a few hours and look for any drips at the PVC joints - it doesn't take much!

[georgeortiz]

I do have a couple leaks. Sorry I had to look up "cavetating". You learn something new everyday. That's why it is so fun.
Anyway, the problem may be that:
1. I have a leak in the plumbing
or

2. the pumps output is too high creating this Cavetating effect therefore creating the air bubbles. The document I saw says that Cavetating causes a boiling effect on the water output.

Correct?

[NaCl_H2O]

Found the corect spelling - it is "cavitation", it is actually vaporization of the water molecules, according to a fluids engineer at work ... "the inlet of the pump has dropped below the vapor pressure of the fluid at its operating temperature. Generally one increases the pump inlet pressure by adding fluid head, like putting the pump at the bottom of the tank or in a well that's deeper than the tank"

[georgeortiz]

NaCl H2O,
O.K. I think I have it. I will go ahead and A try to fix any leaks and second lower my pumps. I have about another 3 feet below tank level. I can lower them 2 feet without putting them in an inconvenient place. If not I will think of replacing the pump with a larger one. Is the bubble output bad for Tank? That is I guess sort of a newbie question isn't it?

[NaCl_H2O]

Is the bubble output bad for Tank? That is I guess sort of a newbie question isn't it?

Some say microbubbles are bad for SPSs, but I read a post from Instar/Larry awhile back that disputed this? Mostly they mess up the visibility in the tank and cause bubbles to colect all over your substrate, etc.

FYI - You don't necessarily want to get BIGGER (GPH) pumps, just better quality pumps. In fact, my MAG7 pumps cavitated MUCH worse than my MAG5s.

[georgeortiz]

Thanks for the help!