Water pumps

[mobilus]

I'm sure someone here has the answer...
I've laid 1" poly tubing about 450' from the dock on our big pod to our small pond which is a few feet higher I elevation. If the situation was reversed, I wouldn't need a pump...however, I do. Here's the question: what's the better deal, running a larger 2" pump (2 in. 212cc Gasoline Engine Semi-Trash Water Pump - 158 GPM) for $199, or a 1" pump (1 in. 79cc Gasoline Engine Clear Water Pump - 35 GPM) for $165? I know that I can only push so much water through the 1" tubing at a certain pressure, and the efficiency of the motor/capability of the pump are factors as well, but which is the better option? If I had electricity back there, I'd use an old pool pump. Your thoughts?

 

[Mendonsy]

I would say go with the 1" pump. That 2" pump isn't going to like the flow restriction much over long periods.

 

[atsah]

I would think 35GPM would work..

 

[BLSXJ]

what are you trying to do? just fill the small pond?

if time is not a factor... the 1" pump should do the job, but its got a small motor and will take longer, but likely less fuel.

the bigger pump is capable of a higher pressure, and flow... it will produce a higher flow rate down your pipe. but will burn more gas with its bigger motor.

 

[Beltzington]

I would say go with the 1" pump. That 2" pump isn't going to like the flow restriction much over long periods.

Can't you just close the throttle some on the 2" pump? I don't know do trash pumps need to run WOT? Seems for $30 more dollars the bigger pump would give him more utility for other jobs?

 

[BrinkME]

With the 1" pump you'll be under 15gpm and with the 2" pump you'll be under 18gpm .... each pump works out to be roughly $11/gpm (calculated flow).

The real killer is the friction loss of the 450' of 1" poly. The restriction of the system is going to severely reduce the actual flow of each pump that they'll both be in the 10-18gpm range. If the 2" pump was capable of higher head pressure, it might have been worth it, but it will only push just a tad more than the 1" pump.

 

[Mendonsy]

Can't you just close the throttle some on the 2" pump? I don't know do trash pumps need to run WOT? Seems for $30 more dollars the bigger pump would give him more utility for other jobs?

You can do that, and in this case it would probably be better. It all depends on how much pressure is required to push the water through the pipe.
I have a couple of 2" semi-trash pumps that I use for irrigation. If the flow gets restricted they get hot rather quickly which I'm sure isn't good for the pump.

 

[RalphVa]

That 2" pump is way beyond the capability of the 1" line. The 1" line is only good for about 10 gpm without incurring pressure drop.

Ralph

 

[mobilus]

Thanks, all. I should have dragged in a 2" line last year, but it's a lesson learned. I had no choice after all, as the 2" pumps were sold out. Looks like the beginning of a drought in my area, so no surprise there. I already had a 1" pump and it has proven reliable, albeit a bit slow. So, I got the last 1" pump on the shelf. The 20% off coupon excludes pumps, but my catfish need water and the bass have plenty, so...