Help with overflow

[mark]

Problem relates to this thread (http://216.187.96.54/vbulletin/showthread.php?t=36380).

Drilled the hole for the 1" bulkhead (~20 minutes with dremel) and put the bulkhead and overflow in place and thought I would test before cutting into my plumbing.

Using a small submersible pump and measuring volume at 300gph found the bulkhead can't keep up. The layout how I planned is like the picture. If the drain pipe is submerged or even a short vertical piece at the end, I get pumping like in the video. If I just have the elbow at the end, the water in the tank backs up above the weir of the overflow.

Tried putting a Tee just after the bulkhead, just before the elbow, again the water level in tank backs up above the weir.

The refugium is a 20g and probably 300gph is a lot but really expected the bulkhead should be able to handle it. Any suggestions?

video (http://s67.photobucket.com/albums/h316/das75/?action=view&current=Ref_vid.flv)



http://i67.photobucket.com/albums/h316/das75/ref_test.jpg

[saltynuts]

is their an air trap. try puting a t in the line to let air out.
just my .02c

[untamed]

The bulkhead and pipe can handle the volume...but...it's about head pressure and flow rate. More head pressure = higher flow rate.

As the water rises, it builds head pressure against the overflow until the flow rate increases beyond the rate of the incoming water. As soon as that happens, the high flow draws down the water level, the pipe gulps air...disturbing the flow rate which then allows the water level to start to rise again.

A 2nd overflow hole would solve your problem, but I'm sure you aren't wanting to do that....so my suggestion is to run a siphon pipe from there into the sump below. Put the intake of the siphon lower than the current outflow. I'm sure a siphon will make everyone cringe...but you always have that other overflow hole to run on if the siphon were to fail.

No harm in trying it, anyway. You can test if it works with a big piece of flex tubing or something.

Believe it or not, another solution would be to put a gate valve on that pipe and close off the pipe until you get a steady state at which inflow matches outflow. Unfortunately, this is a formula for a flood unless you have that 2nd overflow hole to absorb any change in flow.

B

[mark]

is their an air trap. try puting a t in the line to let air out.
just my .02c

Already tried a 1" Tee, with the center pointing upwards (the Tee inverted how you would write 'T') both right at the bulkhead and also at the end of the horzontal run and no joy. On Skimmin suggestion, tried the Tee rotated 90° and placed on bulkhead (picture), still right on the edge of 300gph.

http://i67.photobucket.com/albums/h316/das75/drop_t.jpg

[untamed]

There's more...the water level in the red pail will also affect the flow you get through that pipe. (assuming that the exit of your pipe is below water line in the red pail)

[mark]

Don't want to be drilling another hole or taking a chance with a siphon so guess I'll have to life with <300gph.

There's more...the water level in the red pail will also affect the flow you get through that pipe. (assuming that the exit of your pipe is below water line in the red pail)

Have tried with the discharge above the water level in the pail not any better.

Thought there would be a reduction from 600gph (rating for 1" bulkhead, gravity flow) if the bulkhead was horizontal but surprised it's half.

[Renegade]

would it make a difference if you put the red bucket on the ground below the tank. This should allow gravity have a bigger effect. if your looking at running them side by side try raising the tank up higher as to have a bigger effect. (couple 2x4 stacked until you get desired flow)

Kyle

[Montana]

it looks like the reservor is not big enough ..... the only thing that would work is to throttle the dischargeof the pump. with out tearing it apart........ or drill another hole and add a nother bulk head..:redface: :redface: