Preventing Return Back Siphon Inexpensively And Reliably

[wsboyette]

I have discovered a means of preventing back siphon and subsequent sump overflow without having to purchase an expensive check valve of questionable reliability. As is obvious, it would only take a tiny bit of debris or buildup in such a valve to cause it not to seal completely and cause a flood. A tiny hole drilled in the return at the minimum desired water level inside the tank is enough to prevent back siphon without fail (1/32 - 1/16" is enough). During normal operation, the hole is submerged and (due to its tiny size) reduction of the flow at the return's output is negligible. When the level of the tank drops to the hole during power down, air will be admitted to the return and the siphon will be broken. I am using this on my Berlin setup, and it works great ! Easy maintenance too.... Instead of dismantling and cleaning a check valve, a prick of a toothpick at water change time is all that's needed to ensure continued reliability.

 

[Krish]

Yea, that's all I do. I drill two small holes incase one happens to fail. Always worked like a charm for me and never used a check valve as I don't want to take the chances.

Edit: If I can find a picture, I'll post it, but back in 2004 when I first got into the hobby, I got a return nozzle that went with a wet/dry I had that came with the hole drilled in it to break the siphon. It was an item you could buy seperately, but back then, drilling the hole to break the siphon was the way to go and these days peoples still do the same. I'll look for that picture.

 

[mfinn]

That is what many of us have been using for years, but as krish said, all it takes is a small bit of algea to grow over the hole ( and it can ) or a snail to crawl over the hole at the wrong time and a flood will happen.
Glad to see you mention some routine cleaning. I do mine at every water change too.

 

[Krish]

Here it is...It's a standard nozzle you can buy from many vendors just as you see it in the picture. That hole that is circled comes drilled in it for you to break the siphon.

 

[Maxx]

Another method that is even more fool proof than the one you mentioned is to use math and cut your returns to a certain height.
You need to know how to calculate the volume of a aquarium. LxWxH, then divide the answer by 231. That will give you the volume of your aquarium. Keep in mind, aquarium manufacturers will round up or down to common sizes.
Lets say you have a 120 gallon tank, (48Lx24Wx24H, actually 119.688 gallons)
Lets say your sump is a 75 gallon tank (48Lx18Wx21H, actually 78.545 gallons)

If you're return pipe sits 2 inches below the surface of your display, it will backsiphon approximately 10 gallons of water (48Lx24Wx2H =2304. Divided by 231 = 9.974). So you need to make sure your sump can handle an additional 10 gallons of water. To measure what your sump needs to be able to handle, we start calculating what it takes it add one inch of extra water in your sump. IE for the 75 gallon tank used as a sump in the example, it would be like this, 48Lx18Wx1H and divide the answer by 231 = 3.740 gallons per inch of water added to your 75 gallon sump.

So in order to handle an additional 10 gallons of water in your sump without flooding, you need to make sure your sump water level is at least 2.67 inches below the top of the sump at all times, (10 divided by 3.74 = 2.67), or you could just call it three and give yourself some wiggle room.

If your sump cant handle 10 gallons of added water, then you need to shorten the return line and make sure less of it is underwater. For simple math sake, if you just cut the return line down from 2 inches below the water surface to 1 inch below the water surface, you only need to make sure your sump can handle and additional 5 gallons of water or 1.33 inches....(5 divided by 3.74 = 1.33, or you could give yourself some wiggle room and go with and 1.5 inches in your sump).

This requires no maintenance and doesnt matter if a snail is crawling across the return line, because it will still break siphon and wont flood. I've been doing this for almost 12 years with no floods caused by back siphoning.

HTH,

Nick

 

[jrgilles]

Yea, I also have a backup hole drilled just incase. I think my main syphon break is a 1/4" hole, so should never clog

 

[MGDMIRAGE]

I prefer over sized sumps hehe. The tiny hole in return is a great idea and i know a lot of people use it.

 

[Maxx]

You guys ever have a power failure at the same time a snail was crawling over your siphon break hole?
I have. Little booger got sucked in a bit and blocked the siphon break. That flood sucked.

Bottom line in this hobby...plan for disaster and you'll be better prepared for success.

Siphon break holes work, can fail. As long as you understand the potential issues with whatever system or technique you go with, you'll be alright.

Nick