Hi guys, and thank you for the quick replies.
Do I acid wash? Yes, with 3:1 or 4:1 solution depending on how it looks. I also used the descale stuff that's supposed to prevent build-up and, quite frankly, it worked well enough I had to clean the cell only occasionally.
What % output? 100%.
CSI? I have no idea, but the pool guy says my hardness is borderline very high and he recommended draining the pool some to reduce that. I did drain about 25%.
I have always had a problem with chlorine. All the previous SWG's were IC20's. Last time I opted for the larger IC40 as I hoped it would do the job. Generally, I'd take a water sample up to the pool guy who'd tell me pH and chlorine and such. Seemed to keep things okay, except I've had to buy 3" tablets all along, too.
We also have monsoon season every year, and that just @#$%s with the water quality. There have been some times where I've had problems with algae. In the past, I was able to knock it out, but more recently the flow switch went out on the SWG while we were away. Algae took hold and the pool went green. After replacing the switch, I tried shocking the pool. When that didn't work, I bought some "Green to Blue", and while that did seem to work, I regret putting it in my pool. PITA to vacuum out, and it left stains. Also, I don't know if that did something to the water, or it was the CYA I was told was needed because there was none, but the cell did get a buildup of calcium. However, on the pool guy's recommendation, I used white vinegar instead of acid. It didn't actually dissolve the buildup but did make it real soft so it could be easily removed with a garden hose. Ultimately, I guess it didn't really provide much benefit because the algae came back. I bought a FAS-DPD kit and 12 gallons of liquid chlorine to SLAM the pool, running the pump constantly. Unfortunately, the chlorine depleted quickly. The pH wasn't too out of whack (7.2) but I adjusted up with Borax, and when I ran out of that I added soda ash I had on hand. That got the pH to 7.5, and the water was crystal clear and sparkling, but pretty soon with the chlorine gone, algae started to return, and that's when I noticed the cell LED was blinking. Current state of the pool - water is clear, floor and parts of the sides have light mustard algae.
I don't know what more I can say other than we live outside Phoenix, AZ. When I originally complained to the pool builder about the original IC20 not doing the job, he checked it, said it was fine. Everyone I talked to after that said it will never generate enough chlorine. Last August we replaced the single-speed pump with a VS type. Supposedly, it was better to run at high speed for a bit and then at low speed for a long time. That was supposed to allow for better filtration and chlorination. In a previous post, I asked about the cloudy output from the returns, but it seems that was just something I hadn't notice before. And now, the cell is dead.
So, I figured I'd ask if it was a good idea to replace the SWG with a chlorine feeder. It sure sounds like the answer is likely no.