Stand pipe is sucking air

maddog10 · Post by **maddog10** » Thu Jan 31, 2008 10:11 pm

Dave,
If you are happy, then we are happy.

I have to admit that I am confused too. Doesn't the CO2 reactor dump to the tank, which dumps to the overflow. I just can't remember how it is plumbed. Still seems like all the water ends up in the overflow.

ingg · Post by **ingg** » Thu Jan 31, 2008 10:46 pm

It does all end up in the overflow, on the intake end of things, and that is the problem...

Overflows aren't meant to run inline loops like this, they are meant to dump water into a sump. Soooo, if that intake takes in air bubbles, but then dumps into a sump, it is never noticed, they rise out of and disperse from the sump.

In an inline loop, the air is noticed. Ordinarily, it'd just spit air bubbles back out the other end. What makes it bad for me is that CO2 reactor - now, I have this big fat piece of tube in the middle of the loop, and those air bubbles build up in there, as the water flow slows down in that CO2 chamber area.

If I "trick" the overflow by feeding it from the return, it doesn't have to pull as hard from the tank. This means it doesn't drop water level as much (the waterfall effect goes away), which means it doesn't make air bubbles, which means no buildup of an air bubble in the CO2 chamber - in theory.

In really bad visuals:

At rest, overflow and tank are ---- even

Start to pull water, and overflow and tank levels are _-- overflow low, tank higher. Little body of water sucking from big body of water, and it can only pull it so fast.... so water level in the overflow is lower.

Pull too much water, or pull too fast is a better way to say it, and that height differential grows.

Now, "trick" the overflow by sending some of the return water from the loop into it. Now it doesn't have to draw so much from the tank. Water levels go back closer to ---- even. Eliminates the air bubbles.

At the same time, the pump can draw all the water it wants to, since it is partially feeding itself to fix the overflow waterfall issue.... lots of flow, CO2 bubble broken up.

I'm sure it is going to take some tweaking, but the idea makes sense to me; now to build it, hehe.

maddog10 · Post by **maddog10** » Thu Jan 31, 2008 11:41 pm

I forgot you had it looped. I actually understand it a bit better now.

Before you fabricate the whole thing, is there a way to test it out. Like taking a small powerhead /pump and setting it in the tank with the outlet piped to the overflow, perhaps with a tee and valve to adjust flow into overflow.

Aaron · Post by **Aaron** » Fri Feb 01, 2008 10:04 am

Okay, that makes more sense now. Good description Dave.

Ghazanfar Ghori · Post by **Ghazanfar Ghori** » Fri Feb 01, 2008 11:31 am

Overflows are usually rated for a fair bit of circulation.

ingg · Post by **ingg** » Fri Feb 01, 2008 11:46 am

It isn't the rating, it is the waterfall - it is sucking in those bubbles. It can draw the water, it just can't do it without turbulence.

They are rated to pull 600 GPH, but to pull that down to a sump. I put a 950gph pump on it with essentially zippy head height

- again, because it isn't pushing from a lower body of water, it is just the pipe friction, as it is closed loop...these things are rated the way they are with flow going to another body of water in their heads, is what I've gathered. Salt guys apparently don't think of closed loops, they think of sumps. I never thought to ask, hehe.

SCMurphy · Post by **SCMurphy** » Sat Feb 02, 2008 11:42 am

There is a problem with using the overflows to attach to a canister filter or closed loop, as evaporation occurs there is less and less flow to the filter causing more and more bubbles. Unless you have a sump running side by side with the filter you can't maintain the water level. About the best thing you could do is drill holes in the overflows to ensure that there is adequate water over the intake pipe. This would have to be fixed if you ever used the overflows with a sump.

Ghazanfar Ghori · Post by **Ghazanfar Ghori** » Sat Feb 02, 2008 12:08 pm

I just have an elevated water level - by raising the 'drain' standpipe - the water
is up pretty high - prevents the waterfall effect.

ingg · Post by **ingg** » Sat Feb 02, 2008 10:27 pm

Well, got it fixed!

Scrapped the twin chamber reactor. Went back to my squiggly design, made it out of 2".

Changed out all the long piping from 1 1/2" pvc to 1" hose, barbed in all over the place.

Put a Wye into the return line, and took one side down to 1/2" pipe, and fed it right back into the overflow.

And it is all working! The pump that at one time I could hear at the top of the steps is now quieter then the Eheim it is next to, and no bubbles being sucked in!

Tomorrow, we see how it does with CO2 running through it

Aaron · Post by **Aaron** » Sun Feb 03, 2008 12:55 am

Sweet.

Are you dosing excel in the meantime? Any new growth yet?

Stand pipe is sucking air

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