Determining correct turnover

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scott.lopez

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Oct 25, 2015
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Frisco, TX
The pool builder was nice enough to install a gpm sensor on the return line to the pool for the returns on the side of the pool. However, they put it after the return for the spa, the lines to the spa jets and after both of the returns for the venturi skimmers (venturi skimmers push water, they don't pull like a typical skimmer).

If I close the two skimmers, the return to the spa, and the spa jets the meter shows 45 gpm @ 2000 rpm. For a 16325 gallon pool, that gives me a turnover rate of roughly 6 hours I believe. If I open all of the valves to the skimmers, spa jets and spa return I get a reading of 30 gpm on the sensor.

My thinking is that since all of the water is going back into the pool that the 45 gpm should be used to determine the turnover, it's 45 gpm going through the filter . The pool builder didn't think so, that's why they put it after the spa return, spa jets and skimmer returns.

Even at the slower speed the venturi skimmers work well, I realize I might have to speed up the pump during the day to help move the water faster if the skimmers aren't effective. Will be keeping an eye on this.

The variable speed pump works great, I'm just trying to figure out the best speed. 2000 rpm seems reasonable to me.


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Thoughts?

Thanks in advance.
Scott Lopez
 
You have been with the forum long enough that you should know by now that we don't advocate the turnover method (as well as ozone, minerals and trichlor - all unnecessary). Turnover has little to do with water quality and knowledge of flow rate is only useful for solar or heaters.

Pool School - Determine Pump Run Time

But the best speed for a VS pump is the lowest RPM where everything still works, especially the skimmers.
 
I run my pump at 1100 for everything except when the Polaris is on, anywhere from 4 to 7 hours depending on the time of year and the water looks great. I never bothered to try to figure out how many gallons per hour it is, just started what I thought was high on both RPM and time and keep backing it down till I thought I should probably not go any lower (in truth I think I could go lower just don't want to push it).

BTW love the arrows on the plumbing.
 
Thanks, the arrows are nice. I'm pleased with the pool builder. They went the extra mile on a lot of items.

I cannot run at 1100, the Ozone unit drains at that speed (yes I have ozone and a 65' path back to the pool for it to work, seems to be good so far). I have to run at 1950 which is still pumping a good amount of water through the pool @ 45 gpm.

I hooked a stenner pump up to the iAqualink computer system that injects chlorine into the pool 16 minutes every hour for between 9 AM and 6 PM. This helps to keep the pool chlorine quite stable at roughly 3 ppm throughout the hot days here in Dallas, greatly reduces my daily effort, and in turn is proving to make the combined chlorine easier to manage. I can set the time from my iPad so it's easy to increase and decrease as necessary. Did you do something similar for your chlorine feed?

Also, did you hook up your stenner pump to the iAqualink to control the acid? I've been thinking about doing that. Acid is such a mess if it leaks that I have concerns about the approach. I'd be interested in your experience.

I asked about turnover because I want to ensure that the chlorine is getting well mixed into the pool. Running the pump for a short period of time after adding the chlorine seems like it would cause parts of the pool to have higher concentrations of chlorine then other parts of the pool. I don't mind paying a little extra for the variable speed pumps to run to ensure that the chlorine gets well mixed. I'm quite busy with other activities that keeping the pool maintenance to a minimum is worth the expense (i.e. no algae blooms or other issues).

I did get rid of the pucks, hence the stenner pump, and I no longer use the Nature2 mineral cartridge (as advised by TFP).
 
I asked about turnover because I want to ensure that the chlorine is getting well mixed into the pool.
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Knowing your turnover won't tell you that. In fact, turnovers don't tell you much of anything other than how much you are probably wasting in energy.

However, it doesn't take much run time at all to fully distribute FC. Based upon my own testing, it takes only 30 min on low speed to fully distribute liquid chlorine added in front of one return to reach every part of the pool (something you can test for yourself). BTW that is only 1/20th of a turnover. So other things are probably going to be the limiting factors such as how long it takes the skimmer to clear the surface. But with the Stenner, and robot, you will be able to greatly reduce run time so kudos for that.


I did get rid of the pucks,hence the stenner pump, and I no longer use the Nature2 mineral cartridge (as advised by TFP).
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Awesome, great to hear. The ozone isn't going to buy you much either because it forces you to run at a higher RPM so it will surely end up costing you more. I would dump that too.
 
I'll do change at a time for now. I've had the pool for a year. Switched to bleach last summer so I'm not to concerned about the stenner pump being effective, I check the chlorine daily during the summer so I'll know if there is an issue. Have not gone through a summer with an empty Nature2 cartridge. I verified this morning that the cartridge is completely empty, so this summer we'll see if I have any issues. Next summer I will consider shutting down the ozone. Shutting of the ozone will be a bit more difficult because it does not have it's own breaker in the box, I'll have to track down how it's connected.
 
For my Stenners I was out of Aqua link relays so I connected them to WiFi switches from WiOn that gives me Smart Phone access to the programming. I run them 5 min after the start of the VS pump so I don't have to worry about clock drift. The Acid Stenner has been great was totally worth it just for the fist year as I was adding a ton of Acid. I am down to less than 1/2 were I was when the pool was new but still like not having to think about it. As for spills I am not to worried, I changed the roller tube at about 14 months and from what I have read if a tube does fail it usually fails on the suction side causing the system to loose prime, so a spill is not likely. The only thing I had to do extra with the acid was paint anything that was exposed metal inside my equipment enclosure things like the mounting bolts for the pump screws on Jandy valves stuff like that. I noticed some rust forming about 8 months into using the acid presumably from the insanely small vent hole in the storage tank, so I painted and started to dilute the 31% acid 1:1 and have not noticed a problem since.

When I am done with the stock of roller tubes I have on hand in a couple of years I plan on converting the acid Stenner to a 10gpd so I only have to order 1 type of tube for both my pumps should save some $ and might give me a little longer life on the pump and tubes since they will be running quite a bit less at 10gpd.

The one nice benefit to the WiFi switches I did not expect is in addition to being able to do 100% custom schedule is they have a count down timer. The count down timer is great for a one time adjustment, if you want to bump your numbers for a party or insurance while you are gone for a few days.
 
Thanks for the info. I think I will set up the acid capability. The iaqualink also has the timer capability so I will use that. Pushing a button will be much more fun then getting out the acid every day, even with a respirator I get a good wiff every now and then.

Diluting the acid sounds good as well.

I do have to worry about freezing temperatures occasionally in Dallas so I will need to come up with an approach to clear the line of acid.

Thanks again
 
The freezing point of Muriatic Acid is -46C (-50.8F) (for Hasa; other brands quote even lower freezing points). It better not get that cold here or I'm leaving! :-D
 

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The stenner acid pump works really great. I am able to keep the acid exactly where I need it. Still verifying with the test kit every day just to make sure I'm not putting to much in. So far, I haven't had to manually add acid to the pool.

Thanks for all of the suggestions!
 
Alright, sounds good. Keep an eye on your TA over time. As you add acid it will slowly lower your TA. As the TA slowly drops the pH rise will also slow down. So, theoretically you will need less acid as time goes by.
 
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