Split drain siphoning from one side

[jonelder68]

It’s been a long day. My brains already mush. Anyone have an idea on why my split drain between sump and second tank is siphoning out the second tank as it’s draining into main sump?

Hopefully I can explain this well enough. Overflow is a modular marine. Drains from tank down to basement. Top gate valve is to regulate flow on main siphon drain. After that it Y’s. Left side of Y with other gate valve is to 20L refugium.

As water is coming down drain into main sump it’s pulling water from refugium tank. Can’t get water to drain into refugium no matter what I do with gate valve.

Is the drain too far below water line to drain?

 

[TX_REEF]

so if I'm understanding correctly, the drain from the main tank into the fuge is pulling water from the fuge into the sump. Is that right? If so, I think you could mitigate this by drilling a small (maybe 1/16 inch, just needs to be large enough to allow air in to break the siphon) hole somewhere around here, on the underside of the pipe/fitting, so the hole is above the standing waterline, but also allows any small drips to fall into the fuge and not elsewhere where you wouldn't want it.

 

[jonelder68]

I drilled a 1/8” hole here while waiting on a response. Still no water draining into refugium and seems to just pull air in as the other part of drain into main sump is full of air bubbles now.

Weird thing was it worked fine last week when first starting system. Had to get a new bulkhead to fix a leak and just turned it back on tonight and can’t get it to drain into refugium.

 

[TX_REEF]

Can you replace the current split fitting with a true "Y" to ensure water is forced down both drains? As it stands, it seems the water is simply taking the path of least resistance (straight) into the sump.

 

[jonelder68]

Can you replace the current split fitting with a true "Y" to ensure water is forced down both drains? As it stands, it seems the water is simply taking the path of least resistance (straight) into the sump.

Possibly ya I could. Can’t remember where I ordered it online but visually it doesn’t appear as a true “Y” but it is equally split.

Hard to see but internally theres a flange/baffle that runs about to the middle so it should divert it about 50/50. The side to refugium is also angled downward slope believe about 20 degrees.

Just can’t understand why it worked last week and now it isn’t…

 

[jonelder68]

I believe it’s air locked on the refugium side. Probably higher up than the hole I drilled right above the water line? Wonder if I should install an air tube/vent as high as I can right after the gate valve?

 

[jonelder68]

My pops stopped by this evening and thinks I should move the gate valve to the sump side vs refugium side to regulate flow. With water level in sump tank being below refugium water level he thinks no wonder it’s siphoning and water refuses to drain. Makes sense. Imma install a ball valve on drain line into sump tomorrow and see how that works. Fingers crossed

 

[Poseidon03]

My pops stopped by this evening and thinks I should move the gate valve to the sump side vs refugium side to regulate flow. With water level in sump tank being below refugium water level he thinks no wonder it’s siphoning and water refuses to drain. Makes sense. Imma install a ball valve on drain line into sump tomorrow and see how that works. Fingers crossed

It is syphoning due to pressure of the flow of water is less than atmospheric and causing a true syphon. Look up the python water changer and it uses the same science. Fun fact this is a huge part of rocket science and fluid dynamics.

Another thing to think of on the event of a clog on the main sump area, is there a safety to where the refugium won't overflow? I'd personally raise the refugium and install a drain to the main sump.

 

[jonelder68]

It is syphoning due to pressure of the flow of water is less than atmospheric and causing a true syphon. Look up the python water changer and it uses the same science. Fun fact this is a huge part of rocket science and fluid dynamics.

Another thing to think of on the event of a clog on the main sump area, is there a safety to where the refugium won't overflow? I'd personally raise the refugium and install a drain to the main sump.

Refugium has two 3/4” drains that return to sump first chamber in sump. They’re the 2 drains on the right with the unions next to the light.

Refugium is raised to allow the drains to slope back to main sump. Main sump clogged? Ya that be big problem regardless.

I haven’t looked up the python water changer yet. But will start reading.

 

[jonelder68]

It is syphoning due to pressure of the flow of water is less than atmospheric and causing a true syphon. Look up the python water changer and it uses the same science. Fun fact this is a huge part of rocket science and fluid dynamics.

Another thing to think of on the event of a clog on the main sump area, is there a safety to where the refugium won't overflow? I'd personally raise the refugium and install a drain to the main sump.

Yes python water changer is exactly how it’s been acting. It’s fixed siphoning by an air hole I drilled above the water line. But still won’t flow water. The weirdest thing is last weeks test run it flowed and worked fine. Only variable I think sense pop mentioned water level heights was I might of over filled sump so water level in it was higher last weeks test run.