Microbubble Frustration: Help Needed

[xraydoc]

So I built this sump for my 90, modeled after Melev's model F, which I really liked. However, ever since starting the tank yesterday I have had an unacceptable number of microbulles entering the main tank. My return pump is in the center section, fuge is on the right. Both feed the central return area. Does anyone have any ideas as to how I can eliminate the problem? I stuffed some filter floss in the baffles to no avail and am becoming quite frustrated.

[flipteg]

what is the flow rate through your sump/refugium...?

[sjm817]

Return pump size? If you turn off the skimmer, do they go away?

[xraydoc]

Originally posted by flipteg
what is the flow rate through your sump/refugium...?

Im guessing that the flow rate through the sump is 350-450 gph. My main circulation pump is an Oceanrunner 3500 with flow split (unequally favoring the tank) between the main tank and fuge.

sjm - If I turn the skimmer off the number of microbubbles decreases but they are not eliminated. I see a large number of bubbles exit the main drain and I think that is part of it.

What I dont understand is why the bubble trap is not working. I spaced the baffles per Melev's recommendation of 1" between and center baffle 1" high. I did not build a tower as he does to accept the incoming flow...maybe a fatal design flaw?

[sjm817]

I usually get flamed when I post this, but those bubble traps dont work. I dont know why people use them. The whole premise is the microbubbles float up AGAINST the downward flow through the baffles. Tiny micobubbles have "neutral buoyancy". They are so small, they dont really float very well. When water is traveling though the bubble trap, they are carried right through. Put a bright flashlight against the baffles and you can watch it happen. Add to that, the baffles are spaced close together, and people usually have too much flow. The bubbles just go screaming right through.

[xraydoc]

Well, your not going to get flamed by me because Im watching (frustrated) the exact thing you describe happen in my sump.

I just wish I knew how to fix it.

[sjm817]

The way I think a sump should be set up is to leave the bubbles on the surface. Dont pull them down into the sump with a bubble trap. Keep the source of bubbles at one end of the sump and have the return as far away as possible.

3 chambers
Drain/skimmer | fuge | return. Single baffle between each and the same height. That return pump is kind of big too.

[Ewan]

Try filter socks. They'll take care of that problem.

[xraydoc]

Originally posted by Ewan
Try filter socks. They'll take care of that problem.

Do you put filter socks on the skimmer outlet pipe in addition to the main tank drain?

[Ewan]

I'd just try the drain from the tank at first.

I just run once from the tank, and everything is crystal clear. I change mine out daily.

[xraydoc]

Thanks Ewan, Ill try that, obviously easier than a radical sump redesign.

[xraydoc]

Originally posted by sjm817
The way I think a sump should be set up is to leave the bubbles on the surface. Dont pull them down into the sump with a bubble trap. Keep the source of bubbles at one end of the sump and have the return as far away as possible.

3 chambers
Drain/skimmer | fuge | return. Single baffle between each and the same height. That return pump is kind of big too.

I think that is probably how I should have designed it. I think the OR 3500 is big, but I am splitting the flow over to the fuge and I have ball valves in place to regulate the flow volume to each section. And, I have some unions and a check valve to overcome as well as about 4 feet of head, all said I thought this pump would be a pretty good match. Maybe Im wrong?

[sjm817]

The big problem with the center return is the pump is right next to the source of the bubbles. They have no chance to dissipate to the surface.

Here is another way to fix it. Put the drain and the skimmer outflow through a 100 micron filter sock.

[xraydoc]

What brand do you recommed for the filter sock? Im just worried that Ill have to redesign my sump, which would essentially require a tank tear down, really really dont want that to happen. I should have just designed it intake --> fuge --> return as you said.

[sjm817]

I see Ewan beat me to the filter sock idea. With the sock, bigger is better. They last longer between changes. I only change them once a week.
i use these:
http://www.premiumaquatics.com/Merch...egory_Code=GFI

[xraydoc]

Thanks a lot, I hope that fixes it.

[sjm817]

That sock might be big for your setup. There are smaller sizes too.

[Ewan]

Bigger is better. I work from home, and my reef is in my office, so it's a piece of cake for me to change a sock out daily. You might not like that so much.

sjm817, I agree with all of your suggestions. I also gave up on baffles years ago for the exact reasons you mention. A couple of years ago I would have had my head chewed off for even suggesting a filter sock on this forum, but now I see lots of folks are using 'em.

A smaller return pump would also help quite a bit. Ever since I scaled back my return and added a sock, I've had a very clear display. No more microbubbles!

[sjm817]

The bubble trap thing is something. You will see every sump being built around here employ them. Often very poorly with tight 1" spacing and lots of GPH. Not only does it not work, it wastes space and often makes the problem worse by transporting the bubbles closer to the return pump. My sump is big enough and set up so there is no microbubble problem. I like socks to keep my sump clean.