Calculating Pump for Turnover

davefuze · Jul 11, 2016

Hello TFP!

10K gallon sport pool with 2" main and 2.5" return lines, cartridge filter, SWG and heater.

Equipment and pad will sit 2' below water line and just 20' from it.

Looking at Jandy 2.7 E VS Pump, and trying to understand if based on rough head calcs loss (about 45') at what rpm (lowest setting is 1500 and60 GPM at 10' of Head) I can get 2 turnovers a day, and for how many hours a day I'll need to run it.

Running one water feature off VS pump as well. No spa.

How does the 2.5" return impact requirements, if at all?

mas985 · Jul 11, 2016

Hi neighbor!

No reason to be concerned about turnovers. Turnovers just don't matter to water quality. Start with this article: Pool School - Determine Pump Run Time

If you need more convincing there is a detailed run time study in my signature.

davefuze · Jul 11, 2016

Mark-

I read the article, thank you.

As I have half the gallonage you have, in same area, and I will assume (perhaps not exact) that we have similar bather loads and similar preference for clean water and with SWG and comparable filter and head loss (same heater BTU but don't know your heating desires), am I over specifying a 2.7HP VS pump (only 1 water feature)? I was hoping to keep things clean at 4 hours a day on its low 1500 rpm setting. It appears optimal filtration is to be obtained at 100 GPM. Just looking more to "build it right" from the start. No spa.

mas985 · Jul 11, 2016

The GPM on the filter is not optimum, it is a recommended maximum. Lower flow rates is always better when filtering.

Basically, trial and error is the best way to determine RPM levels. The lower the RPM, the more energy you will save. However, lower RPM also means skimmers and floor cleaners don't work as well.

As for the pump size, with a VS that doesn't really matter other than cost. Do you have a spa?

As for the heater, are you using that for the pool? You will quickly go broke here in CA. Solar will be much more cost effective in the long run.

davefuze · Jul 12, 2016

No spa (separate location).

9500 gallon gunite sport pool (15x26' at max)

400K ASME copper Raypak gas heater on 115' 1.5" gas line; black Pebble Tec, virtually no wind, 75% full sun.

CV 460 filter. 700 Aquapure SWG. Aqualink RSP6 controller.

2.5" suction, 2" returns. Pad sits 2.5' below water line grade (should help w HF loss), mostly short, straight runs.

Jandy VS 2.0 (2.7 HP max) seems like overkill vs. their 1.5 HP pump (and operating 3, 24" sheer descent water features).

Robotic cleaner planned. 1 skimmer, 4 returns, 2 deep heat.

It would seem to me that I would want to shoot for 70-80 GPM net across system components, and I would be able to run a low - mod speed (1500 rpm, or partial 1000 rpm and partial 1750 rpm cycles) on that Jandy JEP pump about 3 hours a day to both retain desired temperature (87 degrees), and filter properly as well as generate ample FC (like .25).

Solar cover at night (anyway that is the plan, free fom shape of 300 sq. ft.)

Am I missing something? Thank you.

Ironically, I have 11.5 kW PV system, but heat pump just doesn't seem to make sense here. I'm on time of use otherwise.

borjis · Jul 12, 2016

3 hours a day seems good if your swg can keep chlorine levels.

I run my pump only 2 hours a day (no swg) and the water is always clear.

davefuze · Jul 12, 2016

Dumb question, should I think about going to higher demand SWG, ie, 1400 w double output in effort to run pump downto that objective of fewer hours, or am I misunderstanding those dynamics? Thank you.

borjis · Jul 12, 2016

I could be wrong but I think I read often that those with swg typically need at least 4 hours.

you might start where you are comfortable and closely monitor/test levels daily or morning / evening when you start,
then dial the time down from there if need be.

mas985 · Jul 12, 2016

davefuze said:
Dumb question, should I think about going to higher demand SWG, ie, 1400 w double output in effort to run pump downto that objective of fewer hours, or am I misunderstanding those dynamics? Thank you.

That is spot on.

Even though you are on PV, using more energy then you need to will still cost you money in buy back so a VS or at least a two speed is a good idea. The VS gives a bit more flexibility but make sure you install a surge protector. There are many on the forum who found out the hard way that they needed surge protection.

It would seem to me that I would want to shoot for 70-80 GPM net across system components,

Not sure what you mean by that but you only really need higher flow rates for skimming and the heater since you have a robot for cleaning. But since you said you will be using a pool cover most of the time you don't really need skimming either. So probably you can run at the minimum speed for the heater most of the time, which you should check because that can be a limiting factor. When you take the pool cover off, you can then up the speed for some quick skimming.