Below is a design I drew up for a nearly silent overflow box for my 55 gal freshwater (going reef in the future) tank. I would appreciate some input on it before I start construction
Features.
Essentially, the box replaces the in-tank pipe overflow for two of the common DIY overflows It still works the same way otherwise. It consists of two independent boxes, one inside the other, the external box is set 1/8" or so below the desired water level, while the internal box is set at the desired level. One of the siphons draws water from the external box, however it is tuned so that it can't handle the entire flow and the remaining water must overflow into the second, higher, box where a second siphon handles the flow.
Because the first box is fully submerged, it will be completely silent. The flow into the second box should be low enough to ensure that the water sheets down the walls of the box creating very little noise. To further reduce the potential for noise and ensure the box remains critter/algae free, I may cover this second box and leave 1/8" gap for water to flow (assuming this box is over 16" long, a 1/8" gap would give more than 2sq in for water flow)
The only concern I have is with the dual siphon idea itself. High flow rates are what ensure that bubbles don't form in your siphon... the first overflow is under full siphon and should draw little air and be flowing fast enough to purge any bubbles; the second overflow has a much lower flow rate though and the water is falling into the box which could increase the amount of air drawn by the siphon. More air+lower flow, makes me worry that this siphon will break in time and leave a mess. So I will use a aqua lifter to ensure that both siphons remains intact.
Has anyone else done a dual overflow box like this. Its really not much different than using two stand pipes of different heights to keep one under full siphon and decrease noise, but it does it in a unique way (Ive never seen it anyway).
Your thoughts?
Features.
- majority of the flow (adjustable) is under full siphon (silent)
- remaining flow is surface skimming
- intended for use in non-drilled tanks (idea could possibly be used in drilled tanks with some adaptation)
Essentially, the box replaces the in-tank pipe overflow for two of the common DIY overflows It still works the same way otherwise. It consists of two independent boxes, one inside the other, the external box is set 1/8" or so below the desired water level, while the internal box is set at the desired level. One of the siphons draws water from the external box, however it is tuned so that it can't handle the entire flow and the remaining water must overflow into the second, higher, box where a second siphon handles the flow.
Because the first box is fully submerged, it will be completely silent. The flow into the second box should be low enough to ensure that the water sheets down the walls of the box creating very little noise. To further reduce the potential for noise and ensure the box remains critter/algae free, I may cover this second box and leave 1/8" gap for water to flow (assuming this box is over 16" long, a 1/8" gap would give more than 2sq in for water flow)
The only concern I have is with the dual siphon idea itself. High flow rates are what ensure that bubbles don't form in your siphon... the first overflow is under full siphon and should draw little air and be flowing fast enough to purge any bubbles; the second overflow has a much lower flow rate though and the water is falling into the box which could increase the amount of air drawn by the siphon. More air+lower flow, makes me worry that this siphon will break in time and leave a mess. So I will use a aqua lifter to ensure that both siphons remains intact.
Has anyone else done a dual overflow box like this. Its really not much different than using two stand pipes of different heights to keep one under full siphon and decrease noise, but it does it in a unique way (Ive never seen it anyway).
Your thoughts?
