Overflows and returns tend to surge, question

[bosworth]

I have a 50g tank with (2) CPR overflows on 1" drains. The overflows are connected to 1" spaflex that travels about 5 ft to the basement below the tank. There is a nice sweeping turn to a horizontal where the water travels about 30 ft to the fish room, where it makes a 90 travels 20 ft turns another 90 travels 10 ft, then 90's and drops 10 ft to another 90 for a 12" horizontal run then another 90 then it drops into the tank.

Each overflow is on its own run, so there are two full runs as described above. The total return capacity it 1800gph but my return pump only pumps at about 1100gph, so I have plenty of drain capacity. I have two modified stockman durso's in the overflows, but it doesn't seem to matter if they are installed or not I still have the same problem.

Should I add a vent somewhere? How can I stop the surging?

 

[itZme]

Did you drill the holes in the top of the Stockman pipes?

Some people put mini ball valves in the holes to be able to adjust the airflow and tune the back pressure in the standpipe.

I never had any luck with those and just went with glass in-tank overflows and drilled my tanks and plumbed them to use the "Herbie method".

 

[bosworth]

The stockmans do have holes, but like I mentioned it still surges with or without them. I was wondering if installing a vent somewhere in the horizontal section would help.

 

[itZme]

You shouldn't need anything on the other parts of the run. Once you get it tuned it should just flow smoothly all the way out. It is surging because it gets too much water built up and then starts to flow faster, then it runs out of water and slows again. Is it actually flushing and sucking air? I think that means the hole is too small. Try asking in the DIY section for better responses. I gave up on all that and now have no air in the drains, no noise at all and no salt creep in the sumps.

Feel free to stop by sometime and check out the way I have mine plumbed if it wouold help you out.

-- Kevin

 

[bosworth]

Sorry I forgot to add head loss to my return. The actual return for my pump is 620 gph. The CPR 90's are actually 600 gph each so I have a total of 1200 GPH of return capacity not the 1800 (sorry, I thought they were 900 gph each). So I know I have extra drain capacity, I added a second line after my tank overflowed twice. How can I adjust the drains to accomodate the surging?

 

[scottfarcuz]

Seems like most of us have avoided hang on overflows because of problems like these. I know Ive never even tried one because of the stories I've read on here about them.

After looking at your build thread I can see you have a real nice/clean setup in a really nice house that I wouldnt wanna flood LOL. I would think hard about draining the tank into a temp tub and drilling the display.

Heck maybe just buy another tank do the overflow, and swap them out. Could sell the other, or use it down the road for QT, Fuge, or frag tank...

By the way the sps frags doing ok for you?

 

[scottfarcuz]

If you want to stick with the HOB you might want to ask in the equip forum. Here is a recent locals thread that was similar, and as you can see the local crowd didn't have a lot of input/experience with them.

http://www.reefcentral.com/forums/showthread.php?s=&threadid=1219891

If you are thinking about drilling Barr aquatics site explains a setup you could do easily, look professionally done, and not lose a lot of tank space.

http://www.barraquatic.com/overflows.php

Locally Paul at first class aquatics makes similar overflow boxes.
http://firstclassaquatics.com/aquarium.htm

Barrs site just explains the box and external standpipe idea well. probably something you could DIY pretty easy, but almost doesn't seem worth it for the $50-$70 Pauls site quotes...