Bean animal - not quite silent

[wesb2013]

I set up my tank a few months ago and installed a bean animal style overflow. It has been silent to the point I couldn't even tell if my system was running out not.


During today's water change I adjusted the return pump so that there would be less flow in the main tank. I figured I'd need to adjust my overflow to the new flow rate to make it completely silent again, however after several hours of fine tuning I still haven't got it right.

I know I'm close because it'll go completely silent for a few seconds then start to gurgle for a few seconds of and on. (videos are in the links below) there are no bubbles in the main siphon, and the secondary pipe has just a trickle of water running through it.

What do I need to do to get complete silence again?

I saw another thread where someone suggested to another user to increase the flow rate, would that actually do anything? I'd prefer to keep the flow rate small.

New video · Sunday, Oct 27, 2024 🎬

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New video · Sunday, Oct 27, 2024 🎬

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3 new photos · Sunday, Oct 27, 2024 📸

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[Midwater]

Yes, all three of your pipes are facing up.

I have it so that the siphon and durso are facing down.

The safety overflow is almost redundant, as if the level rises above the dorso vent, that then becomes a second siphon.

Totally silent. Works with any flow. Easy to tune.

 

[Sassafras]

The description and diagram offered by Midwater is closer to the original Beananimal design and may solve your problem, however, you can have a silent overflow with open top secondary and emergency pipes. Is the noise coming from the sump or from inside the overflow box? I see you have a Modular Marine overflow, just as I do. When the water level in the pump chamber of my sump drops low enough, the extra head pressure on the pump lowers the flow output enough to cause the water level to drop in my overflow box, which results in splashing as water drops from the tank into the OF box. I simply take this as my cue to top up my sump or do a water change, which restores the flow balance. You might check that possibility. If you do opt to keep the main overflow standpipe open, I would shorten it so that it is barely off the bottom of the box, that will avoid surging or a vortex and give you more latitude in adjusting the flow. I have found that when the main and secondary are close to the same height, it make the adjustment very ticky. Other than that, I would add an elbow to the secondary drain line to let the secondary trickle enter the sump under the waterline.

 

[Midwater]

Reference: https://beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system/

 

[wesb2013]

The description and diagram offered by Midwater is closer to the original Beananimal design and may solve your problem, however, you can have a silent overflow with open top secondary and emergency pipes. Is the noise coming from the sump or from inside the overflow box? I see you have a Modular Marine overflow, just as I do. When the water level in the pump chamber of my sump drops low enough, the extra head pressure on the pump lowers the flow output enough to cause the water level to drop in my overflow box, which results in splashing as water drops from the tank into the OF box. I simply take this as my cue to top up my sump or do a water change, which restores the flow balance. You might check that possibility. If you do opt to keep the main overflow standpipe open, I would shorten it so that it is barely off the bottom of the box, that will avoid surging or a vortex and give you more latitude in adjusting the flow. I have found that when the main and secondary are close to the same height, it make the adjustment very ticky. Other than that, I would add an elbow to the secondary drain line to let the secondary trickle enter the sump under the waterline.

The noise is coming from the gate valve. After reading your post, I'm guessing that lowering the flow rate caused the water level to lower just enough to slow a very small amount of air to be sucked down into the siphon. I'm going to try and bump the return pump up just a little to see if that does the trick.

I didn't see the benefit of adding an elbow to the primary siphon when I was designing this. Now I see that doing so would likely prevent the vortex / whirlpool that feeds into the primary siphon from reaching the surface and taking in air.