Durso standpipe tuning

[spaulr]

Long story short. External skimmer on a shelf in my stand kept overflowing. So I made a skimmer box out of plexi, installed a bulkhead and a external durso standpipe on the bulkhead(see the durso website). A 90 is on the inside of the bulkhead, inlet down. All PVC is 1". For some reason I am having a hell of a time tuning this in. I tested it with the outlet (to my sump) above the water by about 1/4" and almost no water drained down and 3-4 gallons almost ended up in my lap, the stand, and the floor. I didn't quite understand that.

I'm running a durso now in my tank. Works great, no problems. Am I having problems here because of the distance from skimmer box to sump is only about 8"?

 

[trido]

Pics? Or could you post a link to the page you are refering to, to save a little research on my part. C'mon now, you cant make us do ALL of the work.

 

[spaulr]

Lol. No problem. You wish is my command.

http://www.dursostandpipes.com/

Then click Popular Modifications, and Click external overflow.

Website is flash based so the link doesn't change. Anyhow, I'll try to post some pics later tonight.

 

[spaulr]

Pics of the setup

There is one more 90 bend that you can't see. It goes into the sump below.

 

[Len]

Hmmm. So is the problem that very little water actually exits out the durso assembly? The short distance shouldn't be an issue (I had a nano with a durso that fed a sump only 12-15" below it). It sounds odd that even if the siphon didn't start, gravity doesn't naturally drain the water.

 

[trido]

Does the durso drain in the lower sump stop below or above the water line? If it is below there could be back pressure keeping the air stagnant in the pipe thus not allowing it to start. That is, if you dont have a hole in the top of the end cap. Have you tried starting it without the end cap all together? A one inch pipe can allow for a max of near 600GPH. Is your skimmer processing more than that? Maybe try a T on the inside of the tank as well (instead).

I have a 1.25" line processing near 1000GPH with three feet of vertical and about 12" of fall with no problems. It did surge until I changed the size of siphon hole though.

 

[spaulr]

Len- tell me about. I almost crapped my pants 8O when the water got to basically the top of the skimmer box. I was like WTF (sorry for the expletive but that's what came out!!).

I tried not having the top cap on. It almost overflowed - got worse. Almost like it was defying gravity. I couldn't and still can't figure that one out. I've since (tonight) added a 45 at the end of the exit so it's about 1/2 under the water line - micro bubbles are driving me batty as well.

Something I did forget was to use tephlon tape on the upper part of the pipe connected to the T fitting and the top cap. This did help things a lot. I'm assuming that air was getting in the gap of the fitting causing some wierd back pressure - all I can figure.

I'm now tweaking the hole size. What I see at this point is the water will drop to the middle or lower end of the fitting in the box....stay steady for a bit, and then rise high, then lather rinse repeat.
Does this mean that the air hole is too small or too large? I'd really like the water level to remain stable. I have an EV90 skimmer and its pretty touchy to water level changes.

 

[trido]

The surging is from the hole being too small. The Hole works in two ways. First, it is a pressure relief when the pipe is initially filling, then it allows air in to prevent a siphon. If you put you finger over the hole of the durso in your display tank you will see a rapid siphon happen until the overflow is emptied enough to break the siphon. The overflow will then fill until the durso fills and restarts the siphon and gains momentum repeating the process. Thus the surging effect.

 

[bleedingthought]

The first thing I would try is to take the cap off and extend the pipe that is at the top part of the tee higher. See how that works out for you.

 

[spaulr]

Bleeding, why would that make a difference?

FYI - I've since increased the size of the air hole and this has helped dramatically. I still get a little fluctuation, but I think that's probably ok.

One more question- Do most people run their Durso's exit above or below the water?

And is there a way to reduce the amount of bubbles that are produced. My return and skimmer return both return bubbles through the bubble trap.

 

[bleedingthought]

Spaulr, I hadn't seen your pictures and thought that the top of the durso would be under the water line on the outside and assumed you were getting water coming out the top. Sorry.

My durso's output into the sump is submerged. There used to be backpressure so I added a tee that has an exhaust at the top. Here's a picture:

Water comes out the bottom of the tee and air/backpressure escapes out the top (open top). Hope that makes sense/helps.

 

[spaulr]

Bleeding, just so I'm clear, you have 2 air exhausts - one at the top next to the intake (not shown in picture) and one at the bottom to relieve air pressure and keep your bubbles to a minimum. Right?

Hmmmm...this will be tricky to do because of space constraints. I'll let you know how this goes.

 

[bleedingthought]

You're clear!

If your line comes down perpendicular to the sump, use a WYE fitting instead of a tee and that might help with the space restraints.