Fine tweaking of CSI for optimal levels

[BasicTek]

Hi all,

So you all taught me to test my pool with my Taylor kit and what the recommended levels are (Thanks a ton!) and now I'm playing with the CSI using the TFP calculator (turning intro a monster)

Currently my CSI is staying between -.2 and -.3 based on the following levels.

size 11K
FC 6 - 7 depending on when I test my SWCG only runs 4 hours a day and runs it up and it slowly drops this level seems good per the CYA/FC chart
CC 0 not many folks swimming in my pool keeps this at 0 unless I test at 25 ml then I may occasionally see .2
PH 7.4 This is always rising and can go up .4 in a day I have been combating it with approx 30 oz of MA per week (no aeration occurring in my pool)
TA 70-90 (Now this has been dropping due to all the MA I'm adding above so I have to add Baking soda every couple of weeks)
CYA 80 (very stable so far)
CH 420 (also very stable but I bumped from 320 to 420 to raise my CSI a bit for my concrete pool)
Salt 3500 (very stable per my Taylor test my Hayward sees it as 3000)
Borates ? (don't use my due to dog that loves drinking salt water don't think I have a test for this either)
temp 88-92 (very well controlled due to screened pool and solar)

The water is fantastic, crystal clear (often invisible at night) and everything seems to be working well. I'm so glad I don't ever have to use a pool store anymore!

From many posts I read a slightly negative CSI is an optimal for my pool (SWCG concrete) and my only small issue is the regular adding of MA and baking soda (seems like I'm stuck in a loop). I haven't seen the behavior change if I try to maintain TA at up to 100 or down at 70, and same with PH (7.2 - 7.8) it always wants to head to 8 if I don't dose it one to two times a week with MA.

Is this about as good as I can get or are there any other pointers? This forum is huge and I can't possibly read everything so I figured I'd ask.

-Tim

 

[mknauss]

Unless your fill water is high in TA or pH you should get to more of a sweet spot of TA and pH that requires less MA. SWCG is a type of aeration (bubbles created in the chamber) such that your pH will always increase a bit. But adding Baking soda and MA is a bit of a 'do-loop'! Showing my age!

You state you have tried a range of TA and pH. Only thing I can suggest is to see if a lower TA (50) might let it stabilize. Otherwise some of our chemistry gurus might need to assist!

Take care.

 

[BasicTek]

You state you have tried a range of TA and pH. Only thing I can suggest is to see if a lower TA (50) might let it stabilize.

Thanks mknauss.

I haven't tried TA 50 because my Hayward SWG recommends at least 80 and letting it go that low sends my CSI down to -.6. I'll try it for a bit if no other suggestions just to see if it changes anything.

I remember seeing you post before with the IC40 and 6k pool, and I thought I was over-sized lol. Will you ever need a new salt cell?

 

[pooldv]

Agreed try TA 50-60 and pH at 7.8.

 

[BasicTek]

Hi All,

I've got the TA down to 60 now, the current full results

FC 5.5
CC 0.0
PH 7.4
TA 60
CH 450
CYA 70
Salt 3200

To note we've had one of the rainiest summers I've ever seen in Florida this year and this week with TA of 60 my PH was 7.8-8.0 so I added MA and got it to solid 7.4 a couple days later it was back at 8.0. To note we had a very rainy day (tropical storm) so I was wondering if the excessive rain (probably 6-8 hours of rain a week on average) could more of the cause of rising PH than the SWG or at least a major factor??? My SWG only runs for about 3.5 hours a day at 20% give or take....

 

[mknauss]

Rain on the surface of a pool creates pretty good aeration. So a pH rise would be expected.

 

[BasicTek]

Ya, seeing it jump .6 in 2 days right after I added MA made me think, but we probably got 12-15 hours rain in that time, that's a lot of aeration... Maybe I won't see it stabilize until our dry season returns in the fall. All things said 20-30 oz of muriatic acid a week isn't that bad....

 

[BasicTek]

Well 50 seems to be my magic #. My TA dropped to 50 last week and it's held the PH at 7.6 for going on 5 days. To note the rain has also been much less the last few days.

I tested all my consistent chemicals and found out how much water I lost from overflowing rain, my salt went from 3500 to 3000, my CH from 450 to 400, and CYA from 80-60. So based on those falling #'s I've had close to 20% drop in all the things that should stay in the pool in like a month....

Anyway I hope the PH remains stable that will certainly be a huge +

 

[BasicTek]

I haven't added any Muriatic Acid in almost 2 weeks, we did get quite a bit more rain and I took the new numbers

FC 6.0
TC 0.0
PH 7.8
TA 60
CYA 70
CH 400
salt 3000

Now in pool math this makes my CSI just about 0 or -0.05 which I think is a good enough CSI.

My Hayward has a Saturation Index and these new numbers have pushed it up to the scaling point +.46 (they say anything above .2 is scaling)

So with PH being a very direct relation on the Hayward SI I could push it to 7.6 with a small amount of MA or should I leave it alone and trust the more complex pool math calculator?