Problem w/Microbubbles and HOB Closed Loop

[banzai75x]

I did a closed loop using melevsreef.com design. It's a hang on the back powered by an Iwaki MD40RXLT. This pump pumps 1200GPH with a 1" intake and 1" output.

I have it sitting on the shelf near the back of the stand so I'm not losing alot of head pressure.

I am having a serious problem with microbubbles. I don't know if the intake is big enough or maybe I have too many outputs. Maybe my outputs are too big as well.

I have a 1" intake over the back.

I am splitting the return to (3) 3/4" returns. One in each corner and also one going down to the back of the tank blowing across the back.

I just did a water test and there are tons of microbubbles. I sometimes hear the pump sucking air. Is it because I have too many outputs? Or should I increase the drain size to 1.25 or even 1.5"?

Is it because I just filled with water and there are bubbles anyways?

I've attached a drawing. Please help.

 

[banzai75x]

Also, I did this test dry fitted. I have not cemented or primed the pipes together as of yet.

 

[Ereefic]

Dry test is probably your problem. It's probably sucking air in somewhere and that's the reason for your bubbles.

Glue it all up and try it again, see what you get.

 

[banzai75x]

Before I glue it up, you think I should make the drain bigger to 1.5"?

 

[Ereefic]

I'm not sure what you mean. You say you have an intake size of 1" correct? With a closed loop you only have and 'intake' and 'outputs'. What is this drain you speak of?

 

[banzai75x]

I'm sorry. I meant the intake. Should I increase the intake to 1.5"?

 

[Ereefic]

I don't think so, as long as the intake and output piping, going to and from the pump are the same you shouldn't have a problem. The pump will only suck as much as it can blow.

 

[banzai75x]

Ok. I will try it. I just thought that if I had a larger intake then there would be more water available for the pump to suck and perhaps not ever have a chance to cavitate.

Also, the microbubbles are only caused by air leaks in the intake side of the plumbing? It won't matter if the output side has air leaks does it?

 

[Ereefic]

If the intake is always submerged then it should not suck air that way.

I believe the only way you'll get bubbles is by sucking air, unless your outputs are not submerged totally.

The loop may need to run awhile to get any trapped air out also.

 

[sreefs]

Glue the pipes you are sucking air on the intake . If you don't mind a larger pipe on the intake it wouldn't hurt.

 

[banzai75x]

Glued everything up and it seems to have helped. I'm letting the system run for awhile because I have a few bubbles that are floating all around the system. I can't tell if it's still creating microbubbles or just blowing the ones around in the tank.

 

[Gooli]

banzai...did this ever clear up for you? i'm having the same problem