Help Me Understand Variable Speed Pumps?

[ddmorris]

I currently have a Hayward 1 speed, 2 HP pump for my pool (21000 gallons) plus a booster pump for the polaris. I have an attached spa with overflow into the pool and little jet thingies at the bottom of the pool that are supposed to... I don't know what they are for exactly. Two skimming baskets. Cartridge filter.

My Hayward has been repaired three times in the last year. The next time it breaks, I want to simply replace it. My electricity bill is through the roof, so naturally I want something energy efficient.

As I understand it, a one speed pump is a bad thing because I am using too much force for the normal filtration, in order to have enough force for the spa (and maybe the cleaner too?) Everyone says a variable speed is better than a two speed, but why? It seems like you could run the pool on low speed most of the time and just turn on the high speed when you are using the spa. My pool guy says that would burn out the booster pump. That doesn't make sense to me (shouldn't the booster pump be built to have enough power to run the cleaner?), but even so, you could run it on high speed only when the booster pump or spa is on. Right? What are the extra speeds for?

I am not opposed to getting a variable speed pump (and I really really don't want another Hayward), but I don't really understand what I am buying, and that bothers me. Anyone want to explain it to a non-techie person like myself?

Also, does the variable pump replace the booster pump, or do you still run the booster pump too? So confused.

[Pool Clown]

It would be ok to get the variable speed pump. I can't imagine why your pool guy wouldn't know how to adjust the new pump to make it work (maybe time for a new pool guy). If you have automation, you can set specific speeds for when certain operations are happening, pool, spa, cleaner, heater, etc. If you don't have automation, most variable speed pumps have "presets" you can use for those specific operations, you just have to press the appropriate button for said operation.

The best way i have found to adjust the speed for enough flow to satisfy the pool cleaner pump is to turn on both pumps and begin to ramp down the filter pump to the lowest speed that will still give you flow out of the return. When ramping down, there will come a point where the flow coming out of the return will turn from positive flow to a suction, or negative flow. At this point, begin to ramp back up till you once again get the positive flow. Also, be aware that as the filter gets dirty, flow decreases. So when setting the speed to satisfy the pool cleaner, find your positive flow then add a couple of hundred rpm. Also it would be a good idea to monitor this flow throughout the first couple of filter cycles to insure the flow is still there when the filter is dirty.