GPH on a 1" Bulkhead/Drain

[SanDiegoReefs]

Ok guys... I need to ask about 1" bulkheads. According to ReefCentral's Drain Size calculator, a one inch drain pipe can handle about 575gph.

"Using the following input parameters
Gallons per Hour = 575

Drain and Overflow sizes are calculated as
Recommended minimum drain pipe diameter = 0.99 inches "

When I setup my tank, I figured that a 1" would suffice, given this info. I ordered a Sen500, which at 4' is rated at about 400gph. I figured that would be decent enough flow for a return line (with only one 1" drain). I also added a SCWD, and those add a lot of head pressure too.

My problem is: with my pump setup, SCWD in place, it should be doing <400gph... but I can't have it open all the way. I have to divert some of the flow into the sump or my tank volume keeps rising. My drain line simply can't keep up, which doesn't make sense. Right now, it's set to about 1/2 of the full pressure, and it's barely trickling out of the return lines. I swear it's less than my tiny RIO-90 (85gph) in my 10g.

Can anyone with a similar setup comment on this? What am I missing? Could it be my strainer that's not letting enough water through? I'm going to test it without the strainer, but I need to get some mesh or something first, I don't trust my snails to stay away from the drain.

I'm pretty sure SoKal has a 1" drain, with Sen500 full blast (no SCWD), and doesn't have any problems. What's the deal with my drain line???

-moore

[nalbar]

i have also worried about this. its why i added vent pipes to both my 1" bulkheads. allowing air into the pipes helps flow. i find out monday when i fire it up.

what i mean is if air cannot get into your drain line it creates a vacum, preventing good water flow. this is why immediately after the bulkhead your pipe size should be made bigger, allowing air to stay in the pipe. this style will not help a vacum right at the bulkhead but can still help flow.

mine goes from 1" bulkhead to 11/2" downpipe to 2" horizonal to sump. with a 3/4" vent on each bulkhead.


nalbar

[SanDiegoReefs]

I actually did setup an External Durso on it for that purpose. I've tried it with different levels of air intake by adjusting the top... and it hasn't made too much of a difference. I will definitely look into it some more...

http://www.rl180reef.com/pages/standpipe/standpipe-doug_closeup.htm -- That's the basic idea I followed.

-moore

[sdboogie]

got any pics of your setup. It's these very reasons why I decided to go with a closed loop and lower flow from the sump. pictures would help find potential problems.

[nalbar]

ok, the bulkhead ratings on reefcentral are set for BULKHEAD ONLY. look at that picture. there is a threaded pipe into the tank side of that 1" bulkhead. that threaded pipe is far less than a 1" pipe. its really a 3/4 pipe (inside dimension). if you unscrew it and measure you will see what i mean. depending on how you did the outside fitting (screw in or slip?) it might also be less than a 1" inside dimension. this is because threaded pipes have to be thicker to recieve the threads. if you add this 'bottleneck' to a vacum at the entrance AND not increasing the size of your pipe after the 90* elbow it could be the source of your trouble. i took a drill and ground out the inside of my threaded fittings and used slip fittings (also ground out) on the out side, making sure all were OVER an inch inside dimension.

none of this really matters on a pressure pipe but on gravity feed it can cause problems, particularly when you try to match pump to bulkhead too close.



nalbar

[nalbar]

ere is mine from the back view. you are looking right at where the pipe increases to 2". notice the two vents sticking up.

[nalbar]

once the tank is turned back around the 2" comes through the hole to the upper right of this picture and goes to the left side of this sump. you can see the return pump (900 gph) in the right side of the sump. nothing complicated, no strange turns, pipe increases at every 'Y'.



i sure hope it works. although if i pump to much water i will divert to my sump.



nalbar

[sdboogie]

moore -
I would stip the system down to purely needed components. Take off the strainer and remove the intank fittings so you just have the bulkhead. I would also use all slip fittings outside the bulkhead. As nalbar said, the threaded fittings restrict flow. Get your system down to basics and see what flow it can handle. Then start adding one piece at a time, like the strainer and see what affect that has, then the inside plumbing and see again. You should be able to narrow the problem down. Maybe you need another bulkhead for dual overflows, redundancy never hurt. HTH :cool:

[sdboogie]

Also, here's a design I used to eliminate the inside the tank fittings. The water never drops below the top edge of the bulkhead.

http://www.sdreefs.com/forums/showthread.php?s=&threadid=704

[SanDiegoReefs]

Alright guys, thanks for the info. My bulkhead is connected (outside) to a 1" PVC T connector that slip fits into the bulkhead. This weekend I'm going to try stripping down the in-take stuff to test it out, so we'll see where I get with that.

I'll be sure and let you guys know how it turns out, as well as post some pictures later today.

-moore

[nalbar]

sd, the reason both moore and i want the inside fittings is to raise the level all the way. plus if the water is dropping into an up pipe your fish/shrimp are less likely to swim in.


but i'm sure you know this!


nalbar

[sdboogie]

I'm going with a DIY skimmer box covering the bulkheads. I figured that the black skimmer box would look better on the black background than a white 90. It also wouldn't protrude (about 1.5") as far out as the fitting. The pic posted is initial testing phase of durso design and doesn't include the skimmer box yet. I'm still trying to get some 1/4" black acrylic to make it out of.

[nalbar]

ahhh, sd, i see. i also thought about that route. in fact i still have not given up on it quite yet. i dont think there is any doubt that you get more flow from a box than a restrictive up-pipe. if you look at reefcentrals flow rates they reccommend pretty darn large boxes to maximize flows. this also might be part of moore's (and my possible future) problem.



nalbar