CSI of -0.48 to -0.61 - Should I be concerned?

[phalcon51]

According to the Pool Calc app my CSI is somewhere between -0.48 to -0.57 depending on my pH, CYA and salt level.

FC = 4.0
CC = 0
pH = 7.4
TA = 70
CH = 300
CYA = 50
Salt = 3280 (strips)
Temp = 70
CSI = -0.48

or

FC = 4.0
CC = 0
pH = 7.5
TA = 70
CH = 300
CYA = 50
Salt = 3600 (drops)
Temp = 70
CSI = -0.57

and if I get my CYA up where I want it:

FC = 4.0
CC = 0
pH = 7.5
TA = 70
CH = 300
CYA = 70
Salt = 3600 (drops)
Temp = 70
CSI = -0.63

Is a CSI at these levels a problem? What adjustments should I make?

Which is more trusted for the salt test, AquaCheck strips or the Taylor drop test?

Thanks,

Gary

 

[duraleigh]

For the best accuracy and reliabilty, the Taylor drops test is better than the strips.

That said, the strips are accurate enough to use with your SWG but they do have a shelf life.

Just me, but I have NEVER had to consider CSI in my pool management. If you keep your parameters within the ranges suggested here, CSI is irrelevant.

 

[solarboy]

I'd raise your TA to 100 or something, unless it's a liner or fibreglass pool, then I'd leave it alone.

 

[Lana537]

Hi

I just fiddled with your numbers on the Pool Calculator, and it seems that if you upped your pH slightly to 7.5, your calcium to 350, and your TA to 90, AND with a pool water temperature of 80 degrees, you'd be at -.19, which is not too shabby for an SWG. (Trust but verify~~ )

Your water temperature won't be staying at 70 for very long before warming up for the summer, right? Temperature counts a good deal with all this.

Lana

 

[JasonLion]

What kind of pool do you have? Vinyl, fiberglass, or plaster/pebble/quartz?

 

[dmanb2b]

The main issue may be temp ...just a guess this time of year, but I would think your water won;t stay at 70deg very long...if your water warms up 10 deg, your CSI should rise by about .1

 

[susa]

>> I'd raise your TA to 100 or something, unless it's a liner or fibreglass pool, then I'd leave it alone.

based on Jason's suggestions in another thread, I would keep TA closer to 50 and allow pH to climb to 7.7--7.8 as the MA demand will stabilize with a SWCG

I keep TA at 60 and pH at 7.7 with the Simpool and am using hardly any MA weekly.

 

[phalcon51]

Yes, I'm purposely keeping the TA at 70 to try and reduce the amount and frequency of MA additions. I try to keep the pH between 7.5 and 7.8 and I seem to be adding about 2 1/2 to 3 cups of acid every 3 or 4 days. I had the pool re-plastered about 8 months ago so that may still account for most of that. I'm hoping the plaster cures within a year and the acid use stabilizes somewhat.

Gary

 

[JasonLion]

The Taylor salt test is more reliable than the AquaChek strips, but it is still about +-400.

I wouldn't worry about CSI much. Both the PH and the water temperature are going to come up noticeably from where they are now. If it makes you more comfortable, bringing CH up to 350 would be good.

 

[guamguy]

I had the same problem when I converted to SWG. After playing with the pool calculator, the simplest way to keep a decent CSI was to maintain a 7.8 pH.

 

[JasonLion]

You want the PH at 7.7 or 7.8 anyway to minimize PH drift.

 

[phalcon51]

You want the PH at 7.7 or 7.8 anyway to minimize PH drift.

If I did that I'd be adding acid daily! It only takes a day to go from 7.8 to 8.0 and beyond the next day.

Gary

 

[JasonLion]

Let TA come down and the PH will go up more slowly. Let PH go up, and it will go up more slowly. Add borates, and the PH will go up more slowly.

By lowering PH below 7.7, you speed up the cycle of PH constantly rising.

 

[phalcon51]

I've already lowered the TA to 70. Are you saying I should go lower? 60? 50? Is the acid demand still likely due to the new plaster from Sept. last year? If so, will the lower TA and/or higher pH still have a beneficial effect on the acid demand, or not until the plaster cures completely?

Gary

 

[JasonLion]

There is an acid demand from the plaster, which won't go away until the plaster finishes curing. There is also an acid demand from TA being above about 40 or 50. It is difficult to say have much of your PH drift is from which cause, only that they are both happening. Borates help slow PH drift from both causes, though borates never eliminate PH drift completely. Lowering TA and raising PH helps reduce or even eliminate PH drift from TA. You can lower TA to 60 without borates, or down to 50 with borates.

 

[phalcon51]

Any downside or potential problems related to having the TA so low?

Gary

 

[JasonLion]

Not really. With TA very low you probably don't want to bring your PH down below 7.5, but there isn't normally a reason to do that anyway. Because of that you have a slightly smaller range for PH to swing from the plaster curing between acid additions, but the total time between acid additions should be similar or even longer, definitely longer if you add borates.