Is a VS pump the right choice for my pool and its current plumbing?

[Mk3supraholic]

First let me describe my pool/ spa and its set up.

My pool, Approx 19,000 gallons sits about 4 feet below my spa approx. 1000 gallons, The spa over fills and waterfalls back into the pool.

The plumbing:

The pump draws water from 3 possible locations: the Spa, the Skimmer/deep end drain, and the vacuum port. one valve selects between pool and spa and one valve selects between skimmer/drains and vaccum port.

The water then filters, goes through the Gas heater (rarely used only on when spa is in use) and solar heater and the swg, then returns to 2 pipes via a valve (Pool and spa) one leads to the spa jets, the other has a valve on its own that directs to the pool returns or to two additional water falls.

My concerns:

With my current single speed pump I draw from the pool only, half skimmer/drain half vaccum, and return half pool half spa with none of the 2 other water falls on unless we are using the pool.

The only way to filter/circulate the spa water is to return the clean water to it and let it over flow into the pool or shut off suction to the pool and only filter the spa water.


With a VS pump The water will trickle down the the stone work leading to algae and mold in all the crevices. It happens now (minor) but i assume it would be worse with hours of trickling water and i assume more efflorescence will occur as well. Unless i run the vs pump at a higher speed and operate it like my single speed so the water flows out like a waterfall.


Any thoughts or ideas?

 

[Pool_Medic]

Savings can be had by shutting it off for a certain amount of time too.

 

[Technikal]

Maybe I'm wrong, but I wouldn't expect properly chlorinated water to grow mold. Seems that would have to be coming from something else.

Variable and 2 speed pump savings are dramatic. I'm seeing over 70% reduction in power usage, which works out to about $65/mth during the summer. Sure you can run your single speed pump less, but not if you're using a swg, or want to enjoy the water features, or want to keep your pool nicely skimmed...

The two best things I've done to my pool are add a swg and move to a 2 speed pump. The swg made maintenance simple. The 2 speed pump made operating it cheap.

 

[Mk3supraholic]

Maybe I'm wrong, but I wouldn't expect properly chlorinated water to grow mold. Seems that would have to be coming from something else.

Variable and 2 speed pump savings are dramatic. I'm seeing over 70% reduction in power usage, which works out to about $65/mth during the summer. Sure you can run your single speed pump less, but not if you're using a swg, or want to enjoy the water features, or want to keep your pool nicely skimmed...

The two best things I've done to my pool are add a swg and move to a 2 speed pump. The swg made maintenance simple. The 2 speed pump made operating it cheap.

where did i say i want to run my single speed less? Im talking about running a VS at a minimal speed for the majority of the day would cause water to only trickle out of the spa. down my stonework and into the pool. or i run it at a higher speed the whole time like a single speed pump. this is a problem caused by my plumbing not having a way of filtering both the pool and spa at the same time without using the waterfall overfill.

This is an issue i have not seen talked about.

 

[Technikal]

Sorry - the comment on runtime was in response to PoolMedic's suggestion that you could get similar savings by shutting the pump off more.

The relationship between pump speed and gallons per minute is linear, so running the same pump at half speed would move half the water. You could set your valves in a way that would divert half of the water flow of your current pump to the spa to get an idea of what kind of water flow you'd get from a similar variable speed pump running at 1725 rpms.

If the flow is not enough to meet your needs, you could consider moving to a more powerful 2 speed or variable speed pump - ex a 2hp 2 speed or a 2.7hp variable. The power savings would still be significant. Compare the pump curve charts of different options against your current pump's to get an idea of how much water each option will move. You can also program the variable speed pumps to run at higher speeds for a short period of the day to get the water turnover in the spa, while running slower the rest of the day.