my DIY durso is a failure

[akula]

Ok here are the stats. just moved into a 75g. I have a mag 9.5 return pump. I have gotten to the point of having everything hooked up, filled up and turned on and I think the first /main problem I have is that the pump is out flowing the durso. the teeth in the overflow are flowing fine. the sump level seems ok. return pump does not have a valve plumbed in and the return piping is just flexible tubing so no hard elbows to restrict return flow until it gets to the up pipe and lineloc fittings. when I maid the durso I put a short riser pipe on the top with a slit cut in the side of it instead of the typical hole drilled in the top end cap. the endcap on mine can slide up or down to cover the slit and control air that way. that shouldnt be a problem but thats where the problem shows up. right now the only way to maintain balanced flow it to have the riser tube and end cap removed from the top of the durso, so it is only acting like a simple standpipe which is super loud. if I put the endcap inplace and try to adjust the air slot, the overflow fills up over the whole standpipe and the sump starts to empty to a point where the pump is exposed to air. with the endcap I can sort of get the airflow adjusted but the water level just keeps going to a piont right where the air slot is and just starts sucking through the slot which is quiter than just running the durso with an open top but the pitch of the sucking noise is really aggrivating. so my guess is that I am still not allowing enough air in to get the drain to flow enough, or the pump is too strong and so I need to cut it back with the addition of a return valve. I kind of doubt the too much pump issue because the open drain is keeping up so I guess I need maybe put a taller riser on the top with a bigger slit and or go to the conventional drill the hole in the endcap type construction?

ok totally confused now because I took and extra length of pipe, stuck it on top with no air slot, put the end cap all the way on and it started to flood but finally eased back to a good level and flow seems ok. no suction noise but getting air fizz in the sump which I assume is air being pulled past the pipe joint seems (nothing is glued together, its all slip fit with teflon tape).

[wasabi]

What size pipe are you using? i used a 2 inch pvc pipe in the overflow and topped it off with a 2"-4" connector with water falling into the 4" then being restricted down to 2".Andy and i both used this method with great results. it is quiet and efficient.i think you could use 1.5" -3" with the same success.

[georgiajams]

Try using a 1/4 in bigger plumbing on the durso than what your actual standpipe is and see if that makes a difference. Like, if your drain is 1in, use 1 1/4 until you get to the bottom. Full instructions are here..

[georgiajams]

Oh, the Durso shouldn't be the limiting factor if it is working right... your teeth in the overflow, if stock, will. To me, it seems like the Durso can actually handle a little more flow than a regular standpipe. Not sure if that is true, but it seems that way.

[akula]

I believe I am using one size up from the drain size as there is a reducer at the bottom. it is working and quiet now. just has no air inlet to adjust which I though was important. it wouldnt run well when trying various amounts of air into it so I just capped it off at the top and the water level settled at an ok level. good enough for me. it just seemed to be acting funny when I was initially trying to adjust it. hopefully it will stay ok.

[georgiajams]

They take a little adjusting, typically. The water should be about halfway up the sideways "T". If you completely cap it off, the water level will be slightly below the desired level... however I've run it like that with no problems (but I guess at that level it has a tendency to make some noise from time to time).

If there is too much air, the water level will go above the desired level. Incidentally, mine is running that way right now, and I don't have any ill effects (no flushing, etc). As long as it is quiet that is all I care

[Daytona955]

Whaat size bulkhead are you using? 1"?

[akula]

it is 1" ( I assume inside diameter) Pvc pipe going into a reducer so I guess the drain hole is 3/4 but I dont really know. it is whatever a standard oceanic 75G is made with. I outted around with it and saw exactly as you discribe. fully capped off it is running just at the T and if I set the cap a bit crocked to allow some air to seep by it will rise to the better level. when I find my drill I think I will try the airline valve in the cap method for air adjustment. it is quite with the exception of the water splash noise due to the lower level in the overflow so the water coming through the teeth has to drop about 3-4 inches. I think my pipe might be a bit tto short because initially the water level would get high enough to get into the air slot under the cap and swamp it, which would cut off the air flow into the drain and it would just start going back and forth from flood to suck. it is running though.