Overflow volume power outage
- Thread starter Doug864
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fsn77
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Display tank length x display tank width x distance below the water level the drain is in the display tank will provide a close approximation of how much water will drain with your return pump off. Whatever units you measure each in, you can convert to gallons with any number of online conversion tools.
fsn77
New member
The water level is going to drain down to the bottom of the teeth on the overflow, then stop pulling water from the tank.
Depending on how the drain is set up in the external overflow, once the water level in the tank drops to a point that water can no longer flow through the teeth, only the volume below the top of the drain in the external overflow can then drain to the sump. If the drain on the external overflow is much lower than the bottom of the teeth that allows water from the tank into the overflow, counting that volume that will continue to drain out of the external overflow will give you a more exact estimate. If you'd like to account for that extra water volume (could be considerable depending on how long your tank is), it's the same principle... overflow length x overflow width x height from the overflow's drain to the midpoint of the overflow's teeth. I say the midpoint of the overflow's teeth because during operation, the water tends to come through the teeth at a point noticeably above the bottom of the teeth. Perhaps that level is different in an external overflow that runs most or all of the length of the tank, but I wouldn't think it's all that different.
Depending on how the drain is set up in the external overflow, once the water level in the tank drops to a point that water can no longer flow through the teeth, only the volume below the top of the drain in the external overflow can then drain to the sump. If the drain on the external overflow is much lower than the bottom of the teeth that allows water from the tank into the overflow, counting that volume that will continue to drain out of the external overflow will give you a more exact estimate. If you'd like to account for that extra water volume (could be considerable depending on how long your tank is), it's the same principle... overflow length x overflow width x height from the overflow's drain to the midpoint of the overflow's teeth. I say the midpoint of the overflow's teeth because during operation, the water tends to come through the teeth at a point noticeably above the bottom of the teeth. Perhaps that level is different in an external overflow that runs most or all of the length of the tank, but I wouldn't think it's all that different.
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