Saturation Index in SWG Tub

[harris7139]

First of all, I wanted to thank everyone who contributes on this forum. It's been an incredible help as I learn the ins and outs of hot tub water maintenance.

I got my first tub (HotSpring Flair) in June 2022 and am really liking it. I am pretty regimented about maintenance and have had good results so far. I use the Dichlor/Bleach method, but have the addition of the FreshWater SWG to help keep the chlorine level in check.

My question is this... I've recently seen that, sometimes, when water drips on the control panel or outside wall panel of the tub, the water dries and leaves a white mark behind. This is easily wiped off with a damp towel, but it got me wondering what the cause was.

At first I thought maybe it was due to the water being salt, evaporating, and leaving behind the salt. Then I thought maybe it was high PH. I've been testing my levels and everything seems to be in check.

I then started looking at my saturation index and realized that my water is technically not balanced. With staying within manufacture spec in regards to CH, I am currently at 50ppm. I understand the low CH to help prevent clogging of the salt cell, but this (among other factors) puts my saturation index way out of line with what would be considered balanced water. I'm wondering if this has any effect on the white residue I am seeing? Page 3 of this guide shows HotSpring recommended levels with the low CH: https://www.hotspring.com/wp-conten...h-water-salt-system-start-up-guide-canada.pdf

My current water parameters:
Capacity: 325 Gallons
PH: 7.6
TA: 60 ppm
CH: 50 ppm
CYA: ~35 ppm
Salt: 1750 ppm
FC: 3 ppm
Borates: 50 ppm
Phosphates: 0

I "shock" it weekly to 12 ppm, or add liquid chlorine after long soaks. Is there anything I should be doing to have better water. Are the white marks and indication that I might be damaging the equipment in any way?

Any advice or thoughts would be helpful. Thank you!

 

[Oly]

CSI is not a concern in your spa because it is not an in-ground plaster tub. If you experience any foaming you can raise your Ca slightly, otherwise you are in fine shape. Keeping track of your CC, combined chlorine is an important tool to monitor your water. Clean your filter regularly or keep a clean spare and replace often. My tub is smaller than yours and is used every day. I drain and refresh my water after 2 months.

 

[PoolStored]

you can raise your Ca slightly

I think you meant CH (Calcium). 120-150ppm will reduce foaming.

 

[Mdragger88]

What you are seeing is probably salt residue -
I get it on my steps

 

[Methuselah]

+1, salt or water spot (calcium)

For perspective, do a titles search for CSI or Saturation Index in this Spas and Hot Tubs forum. There's three for CSI and one (yours!) for the latter vs. 10 pages of threads for pools.

 

[harris7139]

Copy all that. Thanks for the help and insight!

The tub does sit on a stamped concrete patio. It's recently installed, so I'm hoping the seal coat will prevent any major issues with the concrete. I do try and hose it off regularly, more so in the warmer months.

I appreciate the confirmation on the white spots most likely being salt residue. That seems to make the most sense to me.

I haven't been experiencing foaming, except for a little bit when then running jets at max with air injection, but its not bad. I think my main concern in raising CH was to prevent pre-mature failure of the salt cell. I was able to get a full 4 months out of the last one, which was nice.

I do keep a second set of filters and swap/clean them every 1-2 weeks.

I'll search for the other threads about CSI and continue my research. Thanks again!