Dual Overflow Help

[Neo Jeo]

The 2 main concerns are that it provides an edge where snails/fish/algae/debris can get caught instead of passing smoothly through. This makes it the most likely clog point. The other concern is that you can throttle it closed so much that its inherent built in safety won't function. Ideally, when a drain like this starts to clog the water level rises until it goes full siphon. This dramatically increases water flow making overfilling the tank less likely. It sounds like a toilet flushing over and over again when this happens. Without enough excess drain capacity, even the full siphon may not work the way you want.

Thanks Im not using a siphon system just an over flow box. I have a strainer on it so snails wont get in.

 

[Brew12]

Thanks Im not using a siphon system just an over flow box. I have a strainer on it so snails wont get in.

When it comes to drains such as yours they can operate one of 2 ways. Either air can get pulled into them with the water or the air is not pulled in and it is only water. Durso's are designed to pull air in with the water. These can be called partial siphon, partial drain, open drain or any number of other terms. The ones without air being pulled in are called full siphon.

As an example, a 1" Durso can handle around 600gph of flow. That can go up to over 1000gph when a full siphon is established.