I was where you are at about 8 months ago, had the tub about 4 or 5 months then. Things seems out of control, always checking, always adjusting, always the water was out of whack.
Went away for a week, came back to a perfect tub of water. Talked to the girl at the place I get supplies at and who had checked a number of samples for me. She said something and a light went on.
I was trying too hard, checking too often and adjusting too much.
Now it seems like it maintains itself. Check the basics once or twice a week, shock it every few days, toss in some Alkaline up occasionally, and we're good to go.
Also, I neglected it for a couple days over a week or so and it got a little cloudy. Shocked it good a few times, had a bunch of foam. It all cleared up in a day or so.