Siphon Break help!!!

[firereef]

I have 4 locline returns coming out of my overflow through the front and side of the overflow box. They are about 4-6 inches down form the top of the tank. I also have 2- durso drains in the same overflow. How do I do a siphon break on this setup? if the power fails will my tank drain untin it reaches 4-6" down where the 4 locline returns are???what do I do???

 

[GrndHog]

You need to drill a hole in the 4 lines where you want the level of the water when the power goes out. I just had to do this on my system.

 

[firereef]

so if the lines are 5" down...then the tank will drain to that level if the power goes out??

any way to prevent this?

 

[Anemoneman]

Yes. You need to drill 3/16" holes just below the water level in the return pipes from the pump. When the power goes out your tank will siphon down to the top of the skimmer on the overflows or to just below the 3/16" holes, whichever is lower.
If you don't have skimmer boxes and simply have the siphons 4-5" inside your tank than you have a poor design. Gonna flood.

 

[reefrunner69]

Drill a hole in the return line, inside the oveflow box, there will be a small stream going back into the overflow, but it's not a big deal and is how all the premanufactured overflow kits are designed, usually a 1/8 hole in the crook of the last elbow.

 

[firereef]

ok, but wont it still drain as Anemoneman said until it reaches the 5" down to where the return lines are?

 

[reefrunner69]

No, if the hole is in the return line in the overflow and is above the waterlevel of the overflow, as soon as the pump stops, it will suck air and break the siphon. If you not convinced it will work, you could simply put a check valve on the return line

 

[firereef]

but the return lines are 5" below the top of the overflow...so it would drain all that way no?

what check valves would be good to use?

 

[reefrunner69]

You'd have to research the check valves, I don't use them, I use siphon break holes drilled in the return line to suck are and break the siphon It works, once the hole starts sucking air in it, it breaks the siphon. If you want to test it, get a 3/4" ID nylon hose, about 4ft of it. Punch a hole in it about 6" from the end. Stick that end in your aquarium and the other in a bucket, start your siphon with the hole you punched in it (make sure the hole is open, if the nylon has sealed the hole it won't work) about 1/2 under water, let it drain and see what happens when the hole is exposed to the air....

 

[bound_for_obx]

I'm a little confused. Do the return lines come up THRU the bottom of the tank (inside the overflow) and then exit thru the overflow wall 5" below the top of the overflow?

 

[firereef]

yes thats right

 

[firereef]

yes they do. 2 - 1.5" pipes split about 5" from the top of the overflow into 4-3/4" locline returns.

Could I just drill a small hole in the top of the 1.5" splitter and run some plastic tubinb near the top of the overflow and secure it...so it will break the siphon?

 

[bound_for_obx]

I assume the returns are PVC... Can you cut the PVC, extend it higher, make an upside "U" then take it out its original hole in the overflow? does this make any sense too you?

 

[firereef]

yes i guess i could do that...would the tubing not be easier?
extending it would reduce flow alot?? wouldnt it??

 

[bound_for_obx]

I think what you are describing would work. But definitely get another opinion!

 

[bound_for_obx]

Also, I would not place all my trust in a check valve. They are prone to fail

 

[firereef]

ok...another opinion???anyone??

 

[reefrunner69]

I think it would be OK, but I would use rigid tubing to prevent kinking, murphys law says if it can, it will at the most inopportune time

Is the T under water in the overflow? if not, you can simply drill the hole in it. Cause when the pump is pumping, water will be coming out of that tubing, it is only when the pump stops that is sucks air

 

[bound_for_obx]

On second thought, simply running a tube to the surface will not work. Your tank will drain down until it reaches the bottom of the outlet. I think you will need to extend the pipe up, make an upside down "U" and drill your siphon break where ever you need it. Can someone else verify this?

 

[GrndHog]

They go over the top of the overflow and then 5'' below. Not thru the wall of the overflow.