Dual dursos switching drains?

bureau13 · Oct 6, 2023

So I have dual dursos in a single center overflow section, and lately, it's been all-or-nothing in terms of which side is draining. I get little to nothing out of one side, and a torrent out of the other. That was not previously the case, but everything had slowed down due to obstructions and now that I've cleaned everything, I get almost all of the flow from just one side. The weirdest part is that it switches every now and then. I've been running filter socks, so since one side was doing all the draining I've just been running the one sock, but then randomly it switches to the other drain and bypasses the sock altogether. Very annoying

Any ideas why it's doing this?

KrisReef · Oct 7, 2023

Are the drain heights in the overflow at the same level? The one that is rushing has a siphon pulling it down, that they are switching is interesting. When I have an overflow that siphons it is usually lower and tends to pull the most water all day. When these have changed I think it was because a wavemaker in the tank was pushing water towards one end of the overflow, in pulses which allowed for the dominant flow to switch sides?

bureau13 · Oct 7, 2023

They are not exactly the same height, but they are both in a central overflow, so I don't think it's being pushed by wavemakers. I also don't think I have a siphon, because it's not draining down to the strainer and then gurgling.... It's really not overly loud at all. Just weird.

bureau13 · Oct 9, 2023

OK I was wrong about the siphon, or maybe it started getting worse. I had previously stuck straws in the little hole at the top of the tubes to keep them out of the water (turned out the strainers were massively clogged) and I think these were getting clogged. Still weird that they were swapping back and forth but I just pulled both the straws and everything seems back to normal.

Tcook · Oct 9, 2023

Get the 10” strainers from Richard’s site and should have almost no risk of clogging

bureau13 · Oct 10, 2023

That's actually what I have. It turns out even these can clog if you let the system chug away for over ten years with no cleaning (I know, I know....)