I read through the Chlorine Chemistry instructions that Nitro posted - thank you, I've been looking for kind of information.
Our hot tub doesn't get much use; I haven't been in it for a year or more. Sad, I know.
This Thursday we are hosting a backyard party & I'm certain it will get a lot of use. I have been trying to balance the water and pulling my hair out in the process. I initially shocked the spa (treating it like the pool). FC was 20.
After FC dropped to 5, I set about adding my other chems (stabilizer, borax, acid, baking soda) to balance the water based on the Calculator. As you have probably guessed by now, pH and TA are swinging wildly out of control. One moment my pH is 6.8 with a TA of 10. I added 7oz of baking soda to get TA to the recommended 80 and aerated to raise pH only to see numbers jump tremendously: pH 8 and TA 180. So now I'm back to adding acid (4oz) and aerating to see if both will level out nicely. ??
Thus, I happened upon Nitro's excellent tutorial. I am trying my best to separate pool chemistry from spa chemistry. They seem the same yet different.
Here 's my question. I am a bit perplexed. I see in the instructions that is recommended to change out spa water completely every 3-5mos. Why do we need to change out spa water (once balanced, shocked appropriately, etc) when we don't do that for our pools? What am I missing?
So...do I need to drain my hot tub now in order for it to be deemed safe for the party on Thursday or can I continue with my goal of balancing the water since I previously shocked it this weekend? We do have a slow leak. So, water has been replaced at least partially (perhaps half the volume or more) in the past 10 days.
Thanks in advance.