Setting Return Pump Speed

[reelss]

Hi folks,

I am setting up a 120 gallon tank with a 40 gallon sump (holds about 20 gallons of volume) and would like to know what speed should I be running my DC pump at?

Assuming that the ideal flow rate is turning over the total water volume 10 times per hour. Therefore the goal should be to get a flow of 1400 gph.

The pump I have is a Jebao DCT 8000, rated for a max flow of 2113 gph.

Therefore if I run the pump at about 60-70% I would achieve this.

Anything wrong with the reasoning above?

 

[dbl]

I would think its a good starting point. Remember one thing...you'll have some head loss to the pump due to plumbing going up to return. My opinion...if it's a little off either way from 10% you'll be fine. You'll create flow internally via other methods.

 

[foxt]

As was said above, actual flow rate depends on the plumbing to your display tank. Most pump manufacturers will publish a performance graph that shows output relative to head. I could not find a curve for your pump, so I don’t know if you can predetermine a setting. If it were me, I would start at what you suggested, and use a bucket to measure the actual flow rate into your display, and adjust from there.

 

[DCR]

You have to consider the elevation and friction loss to determine the real capacity of the pump. I would typically assume 4 ft of lift from the sump to the top of the tank and 2-3 ft of piping friction loss depending on your pipe size. Then look at the pumps head curve to determine what the flow will be at that total head. If you look at the head curve, the DCT-8000 will only flow 4000 liter per hour or 1100 gph at 2 meters or 6.6 ft of head. This is at max speed. You cannot expect to ever get the so called "rating" which is based on zero head or no lift produced.