I've got the borate level up to around 50ppm in my pool now and it appears to be working as designed.
Despite the record breaking heat, the chlorine level has remained steady with just the tablets in the automatic feeder set to half flow. In the past I'd have to add liquid chlorine even with the tablet feeder on full flow. Plus, I've greatly reduced the pump time to four hours per day so the tablets are probably dissolving at 1/4 the previous rate.
The water really does "sparkle" more with the borate. Can't say that it feels better or not since I haven't been in the pool yet, still too cold. I've got the phosphate level down to 0 thanks to Orenda PR-10000.
Total cost was about $150 for 25 boxes of borate and 7 gallons of acid. It would have been about $400 to use Nisus Pool Proof to achieve the same level of borates. I'm going to slowly reduce the pump time by half hour at a time to see if there is any effect on chlorine level or clarity. Some people are claiming two hours per day of pump time once they add borates, but it's been so hot here lately that I didn't want to start with two hours.
Of course the Nisus web site has to put down powdered borate: "The problem with the other borates sold is that they are high-pH and low-solubility solids. As a result, they take a long time to dissolve and can even break pumps and do other damage if added to skimmers. Secondly, they are very high pH (alkali), so after dissolving, you must re-adjust the pool pH by adding lots of concentrated acid." Yeah, powdered borate is a bit more work because you have to add it very slowly to the skimmer and let it dissolve to avoid pipe or pump issues, but seriously, it's not very difficult. Probably takes 3 minutes to empty a 76 ounce box about three ounces at a time and I was probably over-cautious. The borate powder dissolves quickly in the skimmer. Adding muriatic acid to bring the ph back down certainly isn't very hard either.
The pool store I go to does a borate test which has only three levels, "low, " "okay," and "good," and I think "good" is 50ppm. Borate test strips are difficult to read.
As far as I know, Leslie's does not sell any borate products, and has no incentive to do so since it would greatly reduce the need for tri-chlor tablets, chlorine, acid, and Phos-Free. Nisus claims to be the only borate product, approved for sale for use in pools, in California. From what the pool store told me, the state insisted on classifying it as an algaecide which meant it had to get some sort of approvals. The pool stores that seem to be gung-ho on borates are the ones whose main business is doing pool maintenance, not selling chemicals to the public, because the borates make their maintenance work easier and they use less chemicals.