What does the hole in the top of a Durso Standpipe Do?
Ok, I give. I am thinking about a diy hob overflow. I have seen some excelent threads on them, and have one nagging question. Durso Standpipes have a hole on the top. Why? w/o this hole, there would be an airlock in the drop tube. Is this a bad thing? Is the hole for tuning? Is it to prevent the airlock and lower the drop noise? Is it to start a syphon?
I am planning this for a nano sump, drop will be less than 8". While I can include the T, I just want to know why I should.
58 gallon oceanic, Kessel 360 tun sun, pressurized co2, eheim pimp #179 - 2217 and diffuser