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

[Doug]

Originally Posted by gregzz4

Should I use a union check valve or not?
I don't want to drill my lines.
What's your experience?

Whats the matter with his response?

I have done my tanks that way for 40yrs. Never have I ever used a check valve. My returns have just been under the surface, with the sump holding any back flow.

I also drilled a 1/8th. in. hole for back up but as mentioned, my systems would be fine without.

I liked to drill them om an upwards angle so the water sprayed straight down. Also on the backside, where the piping came over the top. I found snails could not bother it as much when between the pipe and the glass with not much room.

Only snail problem I have had was one the cover the hole partially and the water squirted in the air. That was corrected by the above angle and placement of the holes.

Having the return just below the water line is still the best solution as was said. If its under far enough that back flow will flood the sump, {for whatever reason I,m not sure},then a check valve is the only solution. Although many have run them with great success, I have read many stories of floods from their failure.