Followed treatments, over chlorinated spa

1,284 litre hot tub. Got an 11ppm free chlorine reading (fine for a spa) and a total chlorine reading of 25. The app recommended putting a LOT of calcium hypochlorite in. I thought it was odd but figured it must know what it’s doing. My spa is now full of extra strong bleach with readings off the chart and I really hope it hasn’t damaged it. Now having to drain it, and refill it with cold water which is going to cost me.

Did I do something wrong or does the app have a bug?

Formula set to Chlorine (calc-hypo), custom chlorine max level of 11, everything else default.

So, the app will try to calculate “breakpoint chlorination” if the combined chlorine is above the max range.

In your case, the combined chlorine (total - free) is 14ppm, which is the highest I’ve ever seen, and possibly a bad reading?

If that TC reading was correct, you breakpoint would be over 100ppm, which is absurd.

I’ll put a guard in the shock calculators to not allow breakpoint targets over 20 (which is still :banana: s), gimme a few minutes…

But, in this case, how did you take this total chlorine reading?

Ok, I made the change to all of the official formulas, so the app will guard against irregular total chlorine levels.

As another change, perhaps we should auto-select a formula for spas (vs pools) if your volume is below a certain amount… I’ll put some thought into this as well.

I used a 6-in-1 test strip and it showed 25-50ppm for total chlorine and 5-11 for free chlorine.

I took a second reading to be sure.

Must be something odd going on, perhaps the pipes are full of biofilm… (I just bought the house with the pool and spa)

1 Like

Congrats on the house / spa!

It can be frustrating to start up a system that’s been neglected for a while, but then it’s easier to maintain afterwards.

Thanks for posting your experience with the app here, it’s already made the product better for everyone (current and future users).

I also wonder if I should add some additional messaging that “your readings are way out of range”? I thought that the sliders having a certain range would indicate the normal values, but maybe I could be more direct with that messaging…