Siphon rate off tank very slow

I have a 60 gal cube tank It's drilled in the back. For the bulkhead that is the siphon off the tank, there is an elbow going down. The water is siphoning off about 5' away, but the exit point to my sump is very very slow.

How can I increase this, so I can get appropriate turn over of the water in the tank?

 

Your drain is not a siphon, it is an overflow, and it runs at the exact same rate as your return pump. You can change the pump to increase the flow.

 

+1. With the info given that seems like the problem.
What pump are you running?

 

If you have a drilled overflow then its just a gravity fed drain, not a siphon. The speed of the water going down the drain is the same rate of flow as the return pump after you acccount for the head pressure, up to the physical limits of the drain size. I could be wrong but a typical 1" drainpipe normally handles up to about 600 GPH, so depending on your drain size, make sure your return pump is not too strong for your drain to handle or your DT will flood. In your case, It sounds like you need a stronger return pump to increase flow. What size pump do you have? Remember, at 4 feet of head pressure, flow rate drops off considerably, and after 6 months of continued use, the pump will loose even more flow rate unless cleaned.

 

Im running an Eheim 1260. If I let that go full throttle it will overflow the DT faster than the water can come back to the sump tank. I'll play with the flow rates from the pump; to see if I can get it flowing a bit better.

How can I increase the flow rate back to my sump? I've been messing around with this for some time, can't seem to get it to equilibrium. The sump's return compartment will be pumped dry, then the overflow will catch back up for a bit but things never get to be balanced. Even if I cut power after the DT tank and turn off the ball valves so the DT gets overflow full. If I then turn the valves back on the flow doesn't seem to be where it should.

The return to the sump is lower than the point where it's taken from the DT.
I'm using 1.25" pipes
Ball valves on both sides (DT and sump) side are wide open

 

It sounds to me like you are having overflow issues. If the return chamber in your sump is going down and then your overflow is catching up and so on them it seems like your overflow isn't giving you a consistent flow. Your return chamber should stay the same all the time.
What type of standpipe do you have.
If you have a Durso then you can try drilling 1 or 2 more holes in the cap and insert airline tubing in the hole. This should allow more air water mixture to allow the standpipe to flow at a constant rate.
IMPO it sounds like an overflow/ standpipe issue

 

+1 to ^^^

Also, you do not need to regulate the flow on the drain. The valve provides a good place for something to clog the line, and that may be an issue, as well.

 

+1. I missed that. You should never valve off the overflow side of the piping, only the return.

 

I played with it a bit over the weekend and the only way I can get the return to the sump to keep up is if I let the overflow from the DT build up some head pressure by using the ball valve to stop flow to the sump. Then if I turn it off, the flow will keep up for a short while. then it goes back to where the sump pumps in the water faster than it comes back from the DT.

Im really confused on this.

 

Photos help. What exactly do you have as far as a standpipe, overflow, plumbing size and any fittings?

You should never have a valve on the overflow, 100% open or 100% closed, no in between. Sounds like you need a good standpipe to properly mix water and air for a smoothe flow but again pictures will help everyone here trying to help you.