View Full Version : Anti siphon on return line


haninja
06-17-2007, 12:00 PM
I read about drilling holes on the return line. Also about putting a check valve close to the return pump?
How do you do it?

jeep9783
06-17-2007, 1:00 PM
U can get a one way check vavle from lowes install it somewhere in your return line (slows gph but keeps from back flowing 1/4 of your tank in to your
sump...just a ball vavle that lets water pass through going up but when power is lost the ball shuts not letting back flow to your sump


Chris

tsciarini
06-17-2007, 1:08 PM
An anti siphon hole drilled in youre return line is your best option... check-valves have a tendancy to fail very easily and as jeep mentioned, will inhibit flow from your return pump.

haninja
06-17-2007, 1:26 PM
So where exactly would you drill the hole in the return line?
Assuming I have ¾ PVC setup with elbow joints into the tank.

tsciarini
06-17-2007, 2:12 PM
take a picture of your return, post it and I'll show you....

James S.
06-17-2007, 5:09 PM
Drill a hole in the pvc right above the water line.Typically I would drill a 1/4" hole in the inside corner of the 90% elbow turning down into the tank.Just make sure that the hole is drilled where water will flow nicely into the water,and not in a position where it will flow onto the side of the tank or something and cause salt creep.

tsciarini
06-17-2007, 5:22 PM
1/4" is a little large on a 3/4" pipe IMO but James is right on as far as placement.

wbholwell
06-17-2007, 7:59 PM
I've never done this, but I would think a 1/16" hole would be large enough to break the siphon- it only needs to let in air.

What do you guys think?

glxtrix
06-17-2007, 9:41 PM
I have a very small hole on my return line, not more than a 1/16 I think. Its just below the water line so no more water empties back to the sump than whats necessary. You by no means need a large hole, anything that will suck air once the water level is below will work.....just always check it from time to time to make sure there is nothing obstructing it.

mfinch99
06-17-2007, 11:33 PM
I have heard that it is a good idea to actually drill to siphon holes. That way if a snail is less likely to ruin your day by blocking one hole.

tsciarini
06-17-2007, 11:37 PM
Not to say that it cant happen... but I've always viewed the snail over the anti-siphon hole as an old wives tale.
Seriously tho... statistically, what are the chances that a snail would happen to be sucking on your return line partially out of the water at the exact same time that you lose power?

WOLFIE
06-17-2007, 11:39 PM
So how do you stop the air from going to the main tank?

Form what I hadread you need 2 siphon holes to stop the water draining into your sump. But then air will go in and when you turn your return pump back on it will puss all the air our on your return line into your displace tank.

dsmitchell
06-17-2007, 11:43 PM
These [swing] check valves are much less restrictive than the ones you can buy at Lowes or Home Depot:

http://www.marinedepot.com/md_viewItem.asp?idproduct=FT9044

I have also found that the anti-siphon hole that Oceanic puts in their overflow kit is much more effective (i.e. immediate) if I have this check valve in place. That way the water level in the sump is much lower during power outages.

David

WOLFIE
06-17-2007, 11:46 PM
hmm that may work for me.

tsciarini
06-17-2007, 11:50 PM
I agree that the swing check valves do work better and are less restrictive... however, I have also been standing in front of one during an intentional power off and watched it fail.

I think that with proper design of your returns, atleast two anti-siphon holes and several fail tests... you shouldn't worry too much about it.

If you're intersted... I work in Alpharetta; I should be able to stop by sometime and take a look at your system and give recommendations. Just let me know...

dsmitchell
06-18-2007, 12:11 AM
I agree that the swing check valves do work better and are less restrictive... however, I have also been standing in front of one during an intentional power off and watched it fail.

I think that with proper design of your returns, atleast two anti-siphon holes and several fail tests... you shouldn't worry too much about it.

If you're intersted... I work in Alpharetta; I should be able to stop by sometime and take a look at your system and give recommendations. Just let me know...

Exactly. In my case, with the swing check valve and the anti-siphon hole, there is much less chance of a disaster -- all of my tests have worked so far. I have also noticed that since a check valve keeps more water in the return line, there is less air being blown into the display when the pumps come back on.

David

Xyzpdq0121
06-18-2007, 12:36 AM
I am fixing to test out a seaswirl as my retun but I am wondering how I am going to do an anti-siphon on it without a check valve which I do not want to use!

ouling
06-18-2007, 3:20 AM
You can route the line upwards (almost to water line) but just a bit lower, so you won't have to prime it. This way it stops siphoning when the water goes below the set point, and also you won't have to prime the darn thing, and you get close loop.

James S.
06-18-2007, 4:47 AM
1/4" is a little large on a 3/4" pipe IMO but James is right on as far as placement.

I've never done this, but I would think a 1/16" hole would be large enough to break the siphon- it only needs to let in air.

What do you guys think?


Fair enough,but keep in mind that the smaller the hole,the more chance that salt creep or just nastiness in general will clog the hole,unless you clean it out once or twice a year while doing maintenence on your tank.I believe I used either a 1/4" or a 3/16" drill bit on my 3/4" return.Worked like a charm!

haninja
06-18-2007, 8:58 AM
Thanks all for great information and opinions.

If you're intersted... I work in Alpharetta; I should be able to stop by sometime and take a look at your system and give recommendations. Just let me know...
Tony, I’ll shoot you a PM later this week.

Cameron
06-19-2007, 2:11 AM
The small syphon holes can clog from salt creep or calcium buildup. Personally, I point my return nozzles just above the water line. Unless you are running a high flow through the sump and/or have static return lines, this is the easiest option.

Schwaggs
06-27-2007, 8:29 PM
1/16th is too small IMO. I use 1/4 holes on 1" pipe, that works well. I wouldn't go smaller than 1/8" and no matter what size you drill, put it on your list to clean out the hole every month or so... also, the hole can be slightly below the water line if you are religious about reaming it out on a monthly basis to clean out the coraline.