Sump overflow buffer volume

[RiaanP]

How much does your water level in display drop when the power goes?

To work out the buffer area needed in the sump to be able to handle the extra overflow from display tank in case of a power outage.

How do you do it?

Is my logic right: take 2cm * length and width of water inside tank. That will give you the maximum liters that should or could drain to the tank when return pump stops. (Obviously it depends on your syphon break design.)

So your sump must be able to handle that volume.

To take it further, Take that water volume divide by (length * width) and that should give you the height the water in the sump will rise when the return stops.

I was suggested 2cm drop in display tank. Is that a good guideline.

 

[mnd123]

All I know is that I seriously misjudged this on my new tank and flooded my office

Had to change return so that they siphon until about that, 2cm.

 

[Neil H]

Riaan

i used the same logic with my sump design, the baffle heights we designed on this principle, and i have never had a flood, Just remember if you have an in tank skimmer this will steal a little of your buffer

I think 2cm is realistic, but highly dependant on your siphon break .... i cut a V shape in the outlet of my return, this kicks in extremely quickly

 

[mnd123]

if you have an in tank skimmer this will steal a little of your buffer

Great point Neil, when the power goes, add the volume of whats in the skimmer to the sump too! I have a TS4 and when it drains to the water level it is what caused the flood.

 

[RiaanP]

Ok, to be even more safe than flooding.
I should exclude the skimmer compartment totally from the calculation for the sump length and width. In case I add any Carbon reactors in the future to the first chamber.

So on a tank of 1.5 by .75 width, glass thickness 10mm gives me 1480*730*20 = 21.6L of water.
Sump length (excluding chamber 1) * width is 1000 * 614 (taking 8mm glass thickness into account)
Sump should then be 21.6L / (1000*614) equal to 35.19mm

So a 2cm water drop in the display will result in a 3.5 cm rise in sump.

 

[Neil H]

sounds about right