Opinions appreciated: check valve vs anti-siphon holes in overflow returns

[paddyob]

Originally Posted by gregzz4

No offence, but you're not giving me a long-time user experience with your reply.
I'm looking for user responses with long-time experience.

How do you know how long this person has been in fish keeping.

I guess I won't offer advice.

[reefme]

Just removed the union check valve yesterday and run the nozzle just below water surface. Reason for removing is every time I turn off and on the pump it making stupid noise.

[Cal_stir]

I drilled 2 small holes just below the waterline on each of my locklines, have had no probs for over 2 years, cleaned them @ a month ago and all holes were still flowing.

[MarkoD]

Originally Posted by paddyob

How do you know how long this person has been in fish keeping.

I guess I won't offer advice.

lol dont you know? online post counts are obviously an accurate representation of how much experience you have

[fishytime]

I use both.....my check valve is on a union and I have two.....I swap them out very so often for cleaning....

[Myka]

This topic really irks me. It is beyond my realm of mental capability to understand why someone would design a system that could possibly allow an overflow during a power outage.

Personally, I have no use for a check valve. I think they are a waste of money. I would rather design my sump to accommodate the back flow (who fills their sumps more than 60% anyway??), and design the return plumbing in a way that only an inch or two of water will back flow. To me, relying on a check valve or anti-siphon holes to keep my floors dry is absurd. If the system is designed in a way that the sump won't overflow regardless, then it makes the check valve and anti-siphon holes completely superfluous.

When designing the system, measure from the running water line to the top of the opening of your return line (where the siphon will break). Use an online volume calculator to figure out how many gallons will back siphon. Make sure you include any other volumes of water that may siphon (like a compartment/overflow box that has some silly design). Then add 25% for safety. Then measure from the water line in the sump to 1/2" below the top of your sump. Figure out that volume. If the available space in the sump is more than the back flow volume you're good to go. If the available volume in the sump is less than the back flow volume you need to redesign to make space for the volume or to reduce the volume backsiphoning, and I don't mean to using gadgets like check valves! Redesign by using standpipes, baffles or such in the overflow boxes, or by raising the return opening to make the siphon break higher.

If all else fails, you just can't seem to figure this out then fill your tank up outside with the hose and do a freshwater test run.

[reefme]

+1 to Myka. Very well explained.

[sphelps]

I agree with Myka, the need for siphon breaks or check valves is a result from bad design. I think the majority of experienced people will agree you shouldn't rely on such things. However you may want to add them to prevent full back back flow all the time but your system should still be able to handle the back flow if the breaks or valve fail. If this were the case check valves would be a better option than break holes as they require more maintenance being that they are often plagued with algae growth.

[fishytime]

In my case it's not bad design..... I do my water changes by siphoning from the display most of the time.... Siphon break holes and check valves help keep more water in the display so I can siphon out more crap....

[sphelps]

Originally Posted by fishytime

In my case it's not bad design..... I do my water changes by siphoning from the display most of the time.... Siphon break holes and check valves help keep more water in the display so I can siphon out more crap....

Agreed provided they aren't actually needed.