My wife and I bought a house with a 5-year-old pool this winter and we opened it 10 days ago. Around then I found this site, ordered my TF-100, and did some vacuuming and pseudo-blind slamming with bleach, relying on the OTO and pH tests that came with the house. The pool has gone from cloudy green to colorless and almost clear over this time (bottom drain is easily visible but water's a little turbid still), and I did my first TF-100 test this morning. Here are the numbers:
pH 7.5 or 7.6
These numbers seem like a pretty good starting point. I was surprised that there was no CYA at all in the pool. The test didn't get even a little cloudy. So my plan for now is to begin to bring up CYA, maybe bring up TA a little bit, and watch to keep the pH where it is in the process. Also, I'm planning to do an overnight FC loss test to see if I need to do a proper slam, now that I can measure FC accurately.
Here's my biggest question: since I'm at the start of the season and have zero CYA, it seems I could bring it up by adding pure CYA in a sock to my skimmer as recommended, or I could use some trichlor tabs. Each 3" tab adds 1.6 ppm of FC and 1 ppm of CYA, so could buy a bucket of 30 trichlor tabs and a floater and use these over the next month or two, supplementing the FC with bleach as needed.
Should I consider something like this, or is it better just to use bleach and pure CYA? I guess it depends how much extra FC I'm likely to lose to the sun in the period before CYA comes up, and the costs of the different chemicals. Does anyone have thoughts on this?