I ordered a TF-100, and am waiting for it to show up; in the meantime, I had my water tested twice this week by the local pool store and have made some modifications to the chemistry based on those numbers:
FC:10+ (the pool store tester doesn't show real numbers past 10)
TC: 10 (not real numbers, just more than 10)
pH: <6.2 (again, who knows what it really is, just under 6.2)
TA: 47 (there was also a data point called "Adjusted total Alkalinity", which they say adjusts for pH...that datapoint is 43 if it matters)
CH: 359 (This is actually Total Hardness, there isn't a datapoint for Calcium Hardness, so I dunno what to say about that)
So, based on those numbers, I was advised to use chems to raise the Alk, use more chems to raise the pH, and add stabilizer. I said thanks (said I had some chems at the new house, which was true, but I wasn't sure what I had), and walked out and went down to walmart and bought some baking soda to start on the Alk, since that was what they seemed most concerned about (after reading around, I think I should have been more concerned with the pH, but more on that in a bit). I added a full 13.5lb bag over the course of a couple of days, running the pump continuously. I finished adding this morning around 9am, and this afternoon I took a sample back to the pool store...here's the numbers I got today:
TA: 107 (adj alk 62)
CH: 349 (as mentioned, total hardness)
The good news, I think I have the alk in the range where it should be...which is funny, since I only added 13.5lbs of baking soda, where their original calculation called for 23.5lbs....wow.
The CYA has skyrocketed, which caused me to question the calibration of their machine, which resulted in a blank stare...ugh. Anyway, the CYA seems a huge jump, though the pool was filled with trichlor tabs when we inherited it this weekend. Since the CYA is up there now (higher than I think I ought to be, but not oppressively so) I pulled all the tabs from the pool and hope that the FC will drop over the weekend to a suitable level, at which point I'm going to try to go the liquid chlorine route if I can find an easy supply of the higher percentage stuff in my area.
The pH taking that big of a swing (of course, I don't really know what the original pH was, other than "<6.2") concerns me, and I'm hesitant to toss MA into the pool as I am now suspicious of the pool store readings. Could adding 13.5lbs of baking soda in 18k gallons make the pH swing that wide? I mean, assuming that the pH was just under 6.2 (who knows?) to 8.1 seems too much for that amount (based on the poolcalculator site, that's impossible). It was probably 6 hours after adding the last batch of baking soda that I took the sample, is it possible that had to do with the reading and I should wait longer before getting a sample?
My gut says let it sit like this until I can test with my own kit that's in the mail, but unfortunately, I'm going to be away from home all next week for work. I don't really want to put the trichlor tabs back in as I don't want the CYA to rise anymore than it has, but I'm not sure my wife is going to stay on top of it if I start slinging LC immediately. How long do you think it could sit this way with filter running 12hrs/day (6 high speed, 6 low speed) before the FC drops to acceptable levels/would need more added? The pool is clear right now for what that's worth...
My pool: 18,000gal inground plaster with attached spa that overflows into pool
My pump & filter: cartridge filter, 2HP 2 speed pump
edit: also, I forgot to mention---I started to check other things out equipment-wise, and found the cartridges were completely shot...before I started adding baking soda, I replaced all four cartridges...not sure if that's relevant, but didn't want to leave it out.