My tub came out of warranty in June and I decided to try bleach for any newbies reading this.
So far the experiment has been successful, I know somebody here had tried it with no luck. Although I didn't use bleach all the time I did use it 95% of time; also my tub has had a chlorine lock and keeps chlorine forever. I haven't really used the tub that much since June
This is what I've found: My PH started at 7.8 and has stayed there, I have used MPS a couple of times to shock the water but it continues to stay at that level. I haven't measured my alkalinity but I do know that the rise and fall together (so I would imagine my alkalinity has been a little high too).
I did add calcium to the water to about 200 PPM - nothing would have changed that.
CYA - when I first measured it was around 70 PPM and today it was at 90 PPM. As I said I have used a little dichlor now and then.
The surprising thing is the chlorine lock which doesn't anything to do with the bleach. I can put about 3 PPM in and it stays for days. I even had 2 kids in the tub after being in the pool and it was about 1 PPM. Heck, I even soaked and had 1 PPM left after soaking. It has been there since June and my water has been sparkling clear - this is better than ozone and N2!
This has happened to me in the past and I paniced the first time ... it doesn't seem to be hurting anything so I can live with it.
Just wanted to give an update.
