SWG Percentage vs Equipment Runtime

[Cathy9887]

Hey guys!

Just a quick update on us.. we have been TROUBLE FREE since I found you & started testing my own water (still every other day) with my fancy kit. LOVE IT!! Thank you!!

Question though... we currently have our SWG set "under 40%" (says the husband), and the equipment shuts down at 1am & comes back on at 5am (4 hour down time). Yesterday the FC was 5.5 and today it's 6.5. This is the one thing we have NOT been able to master - chlorine level!

My question is... would it be better to increase the equipment downtime (off at 1am, on at 10am?) or should we decrease the percentage of the SWG?
Or rather... is there any big difference? We would also like to lower the electric bill a tad , so I'm hoping for a combination of both, perhaps.

TEST RESULTS:
FC: 6.5 (up from 5.5 yesterday)
pH: 7.6/7.7 (higher than 7.5, lower than 7.8)
TA: 80 or 90 (turned pink at 80, darkened to red at 90)
CYA: 90
Water Temp: 86*
Faithfully yours......
Cathy

 

[JamesW]

I would say that you could reduce your run time. 7 AM to 10 PM might work well for you.

Note: The IntelliChlor can only be set in increments of 20 % unless controlled by an automation system, such as the IntelliTouch.

 

[Cathy9887]

We have the IntelliTouch.. increments are at 5% I believe.

Thanks for the confirmation on lowering the runtime!! So do you think running at 40% (or possibly 30-35%) from 7am-10pm will be okay on the IntelliChlor?? It's our first season with it, so I certainly don't want to kill it too soon!

C ~

 

[UN1017]

Check my most out here. This will give you an approximate idea on how much chlorine is being produced, so you can make some educated guesses.

 

[PridgNYC]

Dialing in an SWG can be tricky. It'll never be zero maintenance though. Since you gained a point today, you could probably afford to dial it back a little. Personally, I think that it is better to run it during daylight hours when you are likely to lose FC to sunlight. One way to do it is reduce your run time to just daylight hours (when the sun is hitting the pool or you have bathers), test FC before the SWG kicks on, and after it goes off, keep a log with observations like how sunny it was and bather load as well as run time and percentage. Adjust your percentage and run time so that your evening test tends to be around your target FC. If your evening test is close to your minimum FC, add bleach to raise to the Target, and increase percentage or runtime, (your choice), so that, hopefully tomorrow will be closer. If you track your progress and estimate bather load and sunlight, over a couple weeks you should be able to get it dialed in pretty good. You will still need to test frequently, to make sure you stay on target, but you shouldn't need to add bleach very often.

I have an Intex SWG which only allows me to adjust runtime in hours (no percentage output). I currently have mine set for 5 hours of runtime starting at 11:00am. My FC range according to the CYA/FC chart here is 3-5, I usually end up at 4.5 in the evening, if it is 4, I leave it, once it drops to 3.5, I add bleach to raise to 5.

 

[JamesW]

I would say to leave the percentage where it is and reduce the runtime. Then tune the percentage so that your FC is right at about 7.5 % of your CYA.

 

[Cathy9887]

Oooh.. that's a new "range goal" - 7.5% of the CYA. Is that something I missed in the Pool School?!! (eek!)

By that calculation, our FC should be between 6.5 & 7... ??? That seems high from what the TFP gurus have drilled into my head....

 

[linen]

What is you cya level? We recommend 70-80 ppm cya for swgs. At 70 ppm cya you should keep you FC above 3 ppm and at 80 ppm cya you should keep above 4 ppm. See: http://www.troublefreepool.com/pool-school/chlorine_cya_chart_shock

7.5% of the cya level is for a bleach/liquid chlorine chlorinated pools. SWG chlorinated pools can be run at lower FC levels than the 7.5% of cya that was mentioned above.

 

[JamesW]

The chart shows a minimum of 5 % with a target of 7.5 % for SWG.

CYA.......... (7.5 %) Target FC in ppm

60..................4.5
70..................5.25
80..................6.00

5 % is fine if the water is nearly perfect, and the level can be reliably maintained. However, that gives very little room for error. I like the extra buffer for insurance, but it's not necessary.

At a CYA of 90, your minimum is 4.5 ppm FC with a target of 6.75. Anywhere within that range should work well for you and gives you some room to adjust. The key is not to ever go below 4.5 ppm. 5.5 ppm is about halfway between your minimum and target.

 

[linen]

Good point JamesW. Margin is good.

I think I misread your statement and was assuming minimum not target

 

[Cathy9887]

Wow.. so we're actually good then right at 6.5...

K, that means I need to let that sucker run some more cause we're having a small, but all day party Saturday including a few preschoolers & a couple of adults who I know will overdrink their limit. ;-)

Thanks friends!!!

 

[linen]

Assuming from your FC number that your cya is 85 ppm? If so, I would make sure the FC level is always above 4 ppm. Keeping it above 6.5 will make your swg work a little harder. Bottom line, it is a balancing act you do not want to let it drop below 4 ppm, so shooting for higher makes sense...but having it a higher setpoint does use more run time due to losses from the sun.