Siphon rate off tank very slow

First, lets not call it a return to the sump.
The return, is the return line to the tank.

Next,
The overflow is connected to the drain, which is draining to the sump.


It's not a hard concept.
An overflow will, overflow (or "drain") water out of your display tank up to roughly the recomended max rate of the overflow is rated for. Lets use 600GPH as an example. Take your 1260 and put a gate valve on the return line to the tank.
The 1260 does roughly 600gph, which will be prob 200GPH less after say 4 feet of head hight and some elbows.

If that 1260 can return water much faster than the overflow can handle, it sounds like your overflow design needs some work.

We'd need to see some picture of your overflow box and pipes and their sizes. This shouldn't be very hard to resolve.

 

Here is the plumbing off the back of the tank.



tubing is 1.25" PVC.

The DT is in a room separate from my sump tank which is why I have both supply and return from sump shut-off-able.

Here is the best pic I have of my overflow system and bulkhead.



You can see it is a 90 degree aiming downward with a small hole for air to escape to prevent gurgling noise.

If I fill up my DT and turn off the supply to the sump and let it build up some pressure it will flow nicely to the sump. until its caught up, then it stops keeping up with the flow to the main DT. However if I just let it fill up gradually the overflow doesn't keep up.

Seems like it should.

 

Still sounds like your overflow isn't letting the enough water/air mixture to keep a constant flow to the sump. What size is the 90 in the overflow.

Another thing, check valves aren't good. If that's a standard Home Depot check valve you are adding to head pressure for one right there. Check valves give you a false sense of security and I wouldn't rely in them personally.

 

It looks like its about a 3/4" 90 inside the bulkhead.

Here is a pic of my sump



The tube in front is the supply to the DT and the two in back are from the DT. All of it is plumbed with 1.25" PVC piping.

the overflow measures at 55" from the ground at its highest point.

the return to the sump is 50" at its hightest point.

as for the check valve, I've read a lot of differing opinions on it. I don't plan on relying on it exclusively, but I feel it's a nice precautionary measure.

 

I would try plugging the top bulkhead, move the overflow to the lower bulkhead and construct a short Stockman standpipe so it flows smoothly then temporarily do an up and over the back return minus the check valve until you get the overflow straightened out. Check valves are not wanted nor needed if a reef tank and will fail, usually at the worst possible moment.

The numerous 90 degree elbows are restrictions on the gravity overflow and cut your flows tremendously. I would eliminate as many bends as possible and run the overflow straight down the back without the tee and extra fittings. Even use 1" vinyl reinforced tubing and barbed nipples if you can to get a smooth laminar flow without abrupt changes of direction which cause back currents and eddies disrupting the flow. You would have been better served by side by side overflow and return rather than stacked since this arrangement limits your options for a standpipe which is almost a must.

After seeing the sump plumbing you have major issues to deal with. The overflow should be downhill from the display tank to the sump, no headers that rise up such as you have to cause air pockets and again, restrictions. I would place the sump on the floor or very near to the floor and have the pipe go completely downhill from the display to the sump in one shot with no ups and downs.

 

Just exactly what is this 'check valve' going to accomplish anyway?

Wow, like AzDesRat states= MAJOR ISSUES/ITEMS to re-do before this will ever work properly.

If I read your height measurements right- theres a net 5 inch drop for the sumps return?

START over, I'm going to stop here because I'm not trying to put your system down or anything and want you to get the constructive advise you came here for. There are many great minds/builders here to get to restarted in the right direction.

 

this is the start over.

Geezis how effed up is this thing

I am looking for feedback and help on this.

I will say I did not drill the tank, it came that way from my LST. so getting in and making massive changes is incredibly difficult.

I thought I had stuff set up to make this work. Any insight is appreciated.

 

additionally the check valve isn't the issue. The check valve is on the supply from the sump, not the overflow from the DT. I've tested my pump with the check valve in place and it works no problems at all.

 

Well,

Welcome to 3 reef, you came to the right place for some good advice and guidance.

I'll only hit on a few key points that other have also mentioned.
- the return TO the sump (drain) should be all downhill- What did M&M say, Op- there goes gravity.
- The top of your sump, should be below your DT - which will accomplish the gravity thing.
- no need for check valves in a system like yours

It'll be allright, minor changes, will make a MAJOR improvement

 

If you have a tank on teh flloor, how do you siphon off water for changes etc?

That can definitely be moved, it woudl jsut require a lot of work.

I guess I'm perplexed as to why no one can answer the question:

If I let the DT build up some pressure, e.g. turn off the ball valve to the sump. Then turn it on, the flow is what I woudl expect. Then when the rate is equalized, the flow does not stay caught up.

So the flow can flow to the sump at high volume, so irrespective of the elbows, the check valves flow can be at a rate I would expect.

However once it gets to equilibrium, it doesn't stay caught up.

ALL of the plumbing at my sump is below its respective points on the DT. so it does all flow downhill.