Chemistry readings uncertainty

[gnhand]

I recently added a SWG , Hayward T-15 ,to my pool. My readings are on pool math app. In the last week out weather in the north east ( eastern end of Long Island ny). Have gotten hot upper eighties. I have been having trouble keeping the FC level over 3.0. For the past 5 days I’ve been adding 12% LC 48+ ounces every day or so.

I have lost trust in my reading-especially of CYA. If you look at my log I thought I had it increased it to 70 - 75. So today I went to the local leslies. I know there not trust worthy but I had to have another eye in my readings.

They got :

CYA 117 - mine is ~75
FC. 5.5. Mine 4.8
CC. 2.5. Mine. .2
Alkalinity. 46. Mine 70

I didn’t do a oclt test - but will do tonight
Salt. 2402. Mine3200
Any thoughts from the experts.

 

[mknauss]

How much FC are you adding to the pool each day? Your T15 can add 0.4 ppm FC per hour if set at 100% generation.

 

[HermanTX]

Trust your own testing.
There TA is adjusted TA based on CYA so that is not comparable.
Huge difference in CC.

With the heat wave you need to increase the output of the SWCG.
It was good to raise the FC with LC as that does it immediately whereas the SWCG is good at maintaining FC. So maybe set your SWCG to create 3-4ppm per day to equal your loss. You can use pool math to determine whether to increase the pump run time or the SWCG output or a little of both.

 

[gnhand]

How much FC are you adding to the pool each day? Your T15 can add 0.4 ppm FC per hour if set at 100% generation.

Today I increased it to 13 hours at 100%. It had been 9 hours at 60%

 

[mknauss]

OK -- those should be enough. Do the OCLT and let us know.

 

[gnhand]

How much FC are you adding to the pool each day? Your T15 can add 0.4 ppm FC per hour if set at 100% generation.

Everything I add is posted to pool math and every time I change SWG settings I post it as a note on the app

 

[mknauss]

Everything I add is posted to pool math and every time I change SWG settings I post it as a note on the app

Great. It appears just a few days ago you were at much lower % generation values and likely were not producing enough FC.

Try to not change the %generation so much. As long as you are at or near target level FC for your CYA, leave it. If it goes up some, leave it. If it falls to below Target, then raise the %generation or run time.

 

[gnhand]

I plan to do a full set of readings this evening after the sun is totally off the pool and an OCLT at 5:30 or 6am. Then I’ll be incommunicado on the golf course untill mid afternoon.

Today before I went to Leslie’s I read my ph at about 7.0 - 7.1 - which is close to theirs. Should I airate but aiming the return eyeball at the surface or use A ph up product?

 

[gnhand]

Great. It appears just a few days ago you were at much lower % generation values and likely were not producing enough FC.

Try to not change the %generation so much. As long as you are at or near target level FC for your CYA, leave it. If it goes up some, leave it. If it falls to below Target, then raise the %generation or run time.

Will do that. I’m just trying to learn the correct adjustments. It seemed good then when heat hit our area the fc went haywire.

 

[mknauss]

With a TA of 70, your pH will naturally rise. It is in the 7's. No need to force it.

 

[mknauss]

Air temperature has little effect. It might have been increased UV, as I suspect with the heat came clear skies.

 

[gnhand]

Air temperature has little effect. It might have been increased UV, as I suspect with the heat came clear skies.

Yes that’s correct.

The thing that I’m least confident about in my test is the CYA test - the procedure are done exact . But to read when the dot disappears is my issue. I have plenty of light when doing the test - it there is daylight I walk outside and do the readings- if inside I hold the the sample low and I keep moving the sample till drop totally disappears.
But they got 117 and I got 75 or 80. That’s a big difference. So that concerns me. If they are right my target fc would be ~3.0 ppm higher.

But my pool has remained crystal clear the two weeks or so after I switched to the SWG.

 

[mknauss]

Please do not get pool store tests. Just confuses the fact you have the best, most accurate method of testing your pool water chemistry.

You might do well to get the 50 ppm CYA standard solution to see what that result looks like to your eyes.

 

[gnhand]

Where do I get that

 

[mknauss]

Where do I get that

Standard Solutions

tftestkits.net

 

[gnhand]

Done and ordered. Thanks for all the info!!

 

[duraleigh]

Confirming what mknauss said, Leave your pH alone. Test it probably every three days or so looking for any trends.

 

[gnhand]

Confirming what mknauss said, Leave your pH alone. Test it probably every three days or so looking for any trends.

Thanks - I appreciate all the info especially from mknauss and you

 

[gnhand]

OK -- those should be enough. Do the OCLT and let us know.

I did the OCLT test and failed. Results are in my pool math app including notes. I started the slam this morning. I only had 2.5 gallons of lc. Recommended amt was 3 gallons. Since I’m golfing I will buy more on the way home at 1:00 pm EST . I’ll recheck and add more then

 

[drsipe]

It looks like your morning test was around 9:30 this morning, and the night test was around 3:00 in this morning. For the most accurate results, the night test should be after sun down, and the morning test before sun rise. The more time between those test, the more accurate the test will be.