So we bought our spa new back in May of this year (2015). It's a CLS 738, made by Clarity Spas. 340 gallons, with ozone, and one of the filters does have silver chunks in it. The ozone runs for two, two hour filter cycles each day. This is the lowest setting.
I let my wife pick out the tub cause she's the one who wanted it. It was a floor model that had extra insulation added to it because our WI winters get pretty dang cold up here. We paid six thousand, plus another five hundred or so to the Electrician we hired to hook it up.
My wife filled it and set the water parameters at the start. She used dichlor and MPS enzymes. After about 10 days, I used the Spa while she was at work, and didn't add any sanitizer when I was done. The water promptly went cloudy. At that point, I realized that I would need to learn about, and pay attention to the water chemistry. So I read up on it on the innerwebstubes. I discovered the bleach-then-dichlor method, and adopted it using liquid pool shock /LC that i bought at the grocery store. I also ordered the test kits from TFTestkits.
Our Spa gets used quite frequently, around four out of five weekdays it will get used at least once, and then multiple uses daily on weekends. I add a tablespoon of dry acid about every 10 days or so to knock the PH readings back down out of the dark red range because it would slowly creep back up, depending on how much folks wanted to have the air vents open on the jets. I don't much care for listening to all that noise when in the tub, but others like it.
I never did test the CYA levels, but the Pool store test that we did just before we switched to liquid chlorine said 60ppm. I also add a tablespoon of the powdered stuff every six weeks or so.
I also only tested Alkalinity once at the start, and then again after our drain and refill last week. It measured 60 last week, and I can't remember what it was six months ago. I figure as long as the PH stays in range, why should I care what the alk is?
My wife added a bunch of Calcium at the start, and I tested it when I got the test kits, but I can't remember what the number was. It was high, maybe 250-300 or so? I remember testing it again a month later, and it had come down to reasonable numbers on its own, 100-200ppm. At refill last week, I chose not to add, or worry about Calcium. Our tap water comes from Lake Winnebago, and the Calcium levels are reasonable, so I'm not worried about it.
Now, about the chlorine, I don't know what is considered a typical amount. We add (10%) bleach in quarter cup increments (5 ppm), usually one (if the reading is less than 3ppm) before we get in, and then another when we get out. Two quarter cups (10ppm) if it's the last soak of the day, or on a day the tub doesn't get used. Generally, the chlorine will read 2ppm or less, sometimes zero, at the first use of the day. A CC test will reveal a reading anywhere between 1 ppm - and 5ppm. If no chlorine is added on the second day (tub not used), FC will definitely be zero, and CC will be 1 or less. On the third day, the water will have gone cloudy. When I added up all the Chlorine we used over a 4 month period, and divided the number of days, we average about 17-18 ppm chlorine per day.
I am a OTR truck driver, so I am gone all week usually. I try to encourage my wife to add MORE chlorine, but alas, it is a waste of my breath. Also, she is incapable of doing a test. Well, she will do the test if it's a test strip, but I refuse to buy them, so when they ran out, that was the end of that. Sigh. I will admit that it is nice to not have to correct the PH after she has messed with it using those dip sticks. They seem to work alright for chlorine, but PH? Not so much.
One other thing that I will mention, is the foam. Once a week, we run the jets and scoop out the foam/bubbles with a net for about 5-7 minutes. We also wipe down the edge water line with a towel at the same time. This removes some visible grime in the bubbles, makes the foam go away, and noticeably improves water clarity.
It was 5.5 months later when we did our first water change, and I wonder if this had been too long of an interval. I shocked the chlorine levels to 60ppm, and added a tablespoon of ahh-some, and ran the jets for about an hour before I drained the tub. This did produce a fair amount of bubbles, and more grime than what I am used to seeing. We wiped the whole thing out before we filled it. The clarity improvement of the water was very noticeable, definitely more so than a usual bubble skim cleaning. Also, not the slightest bit of foam when running the air jets. I had never seen that before.
Also, I'm curious about what we should be doing with filter maintenance. We have two of them. The main one we just spray out with the garden hose, but the smaller one with the silver chunks my wife says we are not supposed to touch. This smaller one is more expensive to buy (iirc), and seems to not be as durable. Yes, **** does get caught in it, and I always frown seeing that go back into the tub after cleaning the other one.
My own personal feeling is that the silver and ozone are rather gimmicky, so I'd rather bypass these filter devices. There are warranty concerns however. I CAN tell you however that I won't be paying out money to have someone fix that stupid ozone generator. Can I just clip and wire nut off the wires that go to it?