strange durso standpipe problem

[mvartanian]

Hi, I've got an unusual problem with my durso standpipe setup. My tank is a 30 gallon cube that is plumbed to my basement where I have a 20 gallon sump. I"ve got a skimmer in the sump and an external overflow with U tube on the tank. The problem is this, when I put my hand in the tank there is no problem. When I topoff the sump there is no problem. But when I put a pinch of flake food in the tank the external box with the standpipe almost immediately starts filling followed by the tank which comes dangerously close to overflowing. I have an adjustable air inlet for the Durso and if I close the air inlet entirely I can get the level back to normal, then about 1/2 hour later I can put the settings back to a normal level and all is well again. My theory is that the food causes the skimmer to change its water level due to a halt in foam generation but that theory might not hold water because a topoff should trigger the same event but doesn't. Anyone have any ideas? I should add that my durso setup seems a bit touchy, if I don't have the air dialed in just right I either get slurping or I get the level so high I am not surface skimming. Thanks for any help.
Matt

 

[LA-Lawman]

I bet the flake food is dissolvig , changing the surface tension of the water... does the standpipe make slushing sounds only when u feed or all the time...? can you enclose a pic of the setup... we are all visual people here. 8)

I have been running durso's for years with little to o problems.....

you could make the air hole a little bigger and then try to dial it down...

 

[mvartanian]

Sounds like a plausible explanation. The standpipe does not make any sucking sounds during normal operation or during feeding. I have attached a diagram of my overflow rather than a pic because it's pretty crowded in the back. Let me know if it helps. Like I mentioned my durso setup seems awfully touchy, if I let even a little more air in the water level in the overflow will rise about 4 inches. The sump end is not submerged btw.

>I bet the flake food is dissolvig , changing the surface tension of the water... does the standpipe make slushing sounds only when u feed or all the time...? can you enclose a pic of the setup... we are all visual people here.

 

[LA-Lawman]

crap, i am a good speller huh, i lurned to spel in publik skool!

Is the downpipe on the overflow 1"? do you have any flex-line in the system?

how much flow are ya pushin" thru the thing?

 

[mvartanian]

all plumbing is 1" pvc except for a length behind the tank which is some flexible vinyl tubing at a diameter which just fits over the 1" pvc. There are two 90 degree turns in the plumbing going down and I have a ball valve at the bottom which I was using as one part of the tuning of the whole thing. The ball valve is almost completely open. I'm using a Mag Drive 1800 as a return, but due to the head I've got I'm probably only pumping 150-200gph thru the system (30 gallon tank)

 

[LA-Lawman]

why are you ball valving the return... ?

 

[mvartanian]

Without it I get the flushing effect where the level in the outside overflow box goes high then quickly drains out causing the slurping sound, then rises again. This repeats every minute or so. The drain to the sump is not submerged. I read a few posts about people having success with the ball valve so I tried it and found that slightly constricting the outflow fixed the flushing problem. If there is a better fix I'd love to hear it. Thanks for your replies.

Matt

 

[mvartanian]

One thing to add, there is a thread at another forum here:
http://www.reefland.com/forum/showthrea ... #post22570
which, towards the end, explains some of the whys. Basically if the durso standpipe piece is smaller than the rest of the plumbing you can get this effect. One recommendation is to increase the size of the pieces for the Durso, the other is to use exactly the same diameter plumbing throughout. The ball valve works by effectively narrowing the rest of the plumbing.

 

[LA-Lawman]

no problem, i will think out ur problem today. i gonna try and recreate it today. my garage is the plumbing section at homedepot..

everyone else should have chimmed in by then.....