i bet your siphon is at the tank level and not down below. you can add a siphon break where the pipe goes into the tank water by drilling a hole in your overflow pipe and pressing in a piece of tubing, either 1/4" or i used 3/8" on my reef overflow, just make sure the tube is above you water level and it shoud stop all siphoning.
do you hear "slurpping" sounds? that would be the pipe you have trouble with.
at the top of my 1.5" dual overflow pipes you can see where i glued in 3/4" lines to act as a siphon breaks when i was setting my tank this time. sorry i don't know how to "draw on a pic" or i would have added arrows or something
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When that bomb you built explodes it is going to take out 4 city blocks. lol.
on the upside the city is safe, it's 7 miles away
