Last Minute Double Check

[daveydoodle]

Before ordering this, I just want to make sure the numbers are correct. It's been downsized to a 150 gallon tank, but my question is with two (2) 600 gph overflow boxes, a 40 gallon DIY wet/dry sump, is the Supreme Mag Drive 1200 going to be enough pump at a 5 foot max head height? Am I correct in aiming for just under the amount of the overflow gph? (1200 gph overflow v. 1120 gph return) Or should I buy the Mag Drive 18 (1800 gph) with 1200 gph @ 5 foot head height? If it's too strong I could use a ball valve, but won't that create more pressure on the motor?

Any other variables I'm forgeting to consider? Here's a chart for Mag Drive.

http://www.mops.ca/skus/wp/Danner_Flow_Chart.html

 

[daveydoodle]

Anyone?? What pump are the 150 gallon tank keepers using? Any experience with too low gph or too high?

 

[dawnmarie]

I would go with the 18 . Put a tee in the return line with a ball valve and return any unneeded flow to the sump. By bypassing part of the flow instead of restricting the output, your pump will be much happier.

 

[swk]

I'd vote for the mag 12. Uses much less electricity than the mag 18 and will turn your tank over plenty of times even at 5' of head.

 

[daveydoodle]

Is it better to err on the side of too much, and just redirect or control what you don't need (extra gph in this case) versus not having enough power and being stuck at that?

 

[jsodwi]

YOu could go either way on this one Mag 12 with a moderately stocked tank will be fine. I've used a bigger pump as stated above hooked it to a tee with a ball valve and recirculated it through the sump too. YOu will have to play with the ball valve to get it set to where the tank wont overflow. Where just running the 12 you wont have to worry about it. I wouldn't just get the 18 and run a ball valve to slower flow, eventually you will burn out the pump..I think it comes down to your preference

 

[Toby_H]

Is it better to err on the side of too much, and just redirect or control what you don't need (extra gph in this case) versus not having enough power and being stuck at that?

It's better to have more flow available, and then only use what you need... than to want it and not have it...

But consider the increase in initial cost and increase in electrical use and decide if the benefit is justified by the price. Since the flow rates are so close, I couldn't blame anyone for making either decision...


Added - Which is why we do not recommend using "straight drive" pumps which have a shaft connecting the impeller to the motor. These pumps will not loose gph when dealing with restriction, instead they work harder (consuming more electricity and cerating more wear and tear) to keep up. Naturally at some point they will loose gph but at this point they are working very hard and are at risk of overheating and/or ceasing.

By bypassing part of the flow instead of restricting the output, your pump will be much happier.

There is little value in recirculating the "extra" flow, but there is no harm in doing so. Personally I wouldn't do it unless the recirculated flow fed some aspect in my sump (for example UV light or algae scrubber).

Aquarium pumps are Magnetic driven, meaning the only thing connecting the impeller to the motor is a magnetic connection. Thus this connection simply slips when the impeller is restricted. So absolutely no additional wear and tear nor electrical use is generated when reducing the output of the pump via restriction.