Trouble balancing the water!

[Geargoesdown]

Ok, I'm sure this as been asked over and over again. But here goes.

I use the Taylor test kit and it has the water balancing wheel. When I put in my numbers my "saturation index" is at -0.3. To my understating that is getting in to the corrosive side. Is this ok, or do I need to make changes?

Here is my last test results:
FC 4.5
CC 0
Alkalinity 60 (this is where i found that my PH will stop rising so much and has stabalized)
PH 7.4
CH 180
CYA 40
Water temp 100

Pool store told me to never go above 100 for the calcium hardness because it will deposit everything on the heater, but that doesn't make scenes to me.

Any suggestions?

 

[pooldv]

-0.3 on the CSI scale is not corrosive. -0.6 and lower is corrosive. But, in a spa there is no plaster finish to be effected by a corrosive finish. Corrosive water dissolves calcium from plaster finishes causing etching. That is not possible in a fiberglass or acrylic hot tub. We recommend lowering TA to 50 in a spa. Over in mine at 0 and pH at 7.6 to 8.0 for many years with great results.

Water can also be corrosive to metals but as long as you keep your pH at 7.0 or higher there is no worry about metal corrosion.

CH above 100 is fine, even up to 200 or 300. The water won't deposit scale on the heater element as long as your pH stays below 8.2 and your CSI stays below +0.6.

More here about managing pH and TA in a go tub, How do I use Chlorine in my Spa (or pool)?

 

[kimkats]

I also suggest you use our Pool Math app. You can download the free version from any devise. You can also use Pool Math at the top of this page if you would. I like our Pool Math as you can change the numbers to see how they all work together. These is a little learning curve so just poke around and ask questions.

Kim