Yeah, I never dealt with cleaners and such, unless the pump quit working. But I have done thousands of spa warranty repairs, and have even had to deny a few, but never once was asked for chemical maintenance records. I did see a weekly maintenance company get stuck with the cost of the repair that was denied under warranty due to chemistry issues, as they had maintained it from day one.
I don't have ph problems. In fact, I do it the way I do specifically to AVOID ph problems. I spent 25 years fixing them for a living, I have seen what bad chemistry can do, and the last thing I want is more work at home. I do it my way because it's what works best and is easiest for me. Dichlor is 7.0 in solution, and hypochlorous acid is acid whatever the source. But spas have so much aeration going on, especially those with 24/7 ozone injection, that I personally need to add a bit of acid a couple times a month, and I keep my air control valves closed when not in use. Now trichlor (tablets) are around ph 3, and are the second worst thing you can do to your spa, right behind freezing it solid.
I also personally wouldn't shock with dichlor, just due to the cya. I drain often, but not weekly. I rely on ozone for oxidation (shocking) except in the fairly rare instance of a spilled drink or a dog jumping in (a real risk at my house), and I use liquid then.
I did notice that your bleach addition did not show any ph rise on that app. Sodium hypochlorite has a ph of 11-13 depending on concentration, and is only 5-10% available chlorine. Dichlor is ph 7 and approximately 60% available chlorine. The ph should be much more drastically changed by bleach than dichlor. My experience with liquid chlorine comes mostly from public pools that had automated feeders for liquid chlorine, and acid (or CO2) to counter the ph rise from the sodium hypochlorite. Don't those of you who use bleach in your spa fight high ph regularly? I would think you would, but have never used it for regular maintenance in a spa myself. I have shocked weekly with mps when I have a tub without ozone, and fought ph in those. I am not a fan of mps.
I agree wholeheartedly that low ph/alk is bad for alot of things in both pools and spas, but so is high ph/alk, especially in spas. Scale is slow death to your electric heating element, air injection system, ozone injection system, rotating jets, filters, and magnetic drive circulation pumps. Not to mention flaking flex hose and sandpaper seats. It beats the melted jet gaskets, leaking glue joints, corroded pumps, and shorted heaters of low ph, but not by much.
But, in all fairness, here in Missouri our water is high everything and I have to work at fill to get it down in range. With the topping off from carryout and kids splashing I could have another variable in my equation.
Sorry for the book, it's late and I'm rambling.
I did that once with dichlor & when i went to rinse the filter the next day it was still sitting on top of it eating away at the plastic.
no telling what it looks like inside now.