thanks for the responses! Pooldv, I hadn't actually calculated it the way you did. The apples to apples comparison is helpful. I've never bought pucks either, I'm sticking with TFPC for now, but I want to understand the "why" rather than just blindly following along. From what I've read on this site I think that having users understand what's going on with their pools- and why- is one of the things TFP is all about.
Getting back to those numbers- my local Lowes sells 35 lb buckets of trichlor tablets for $80. Per PoolMath, 35 lbs of trichlor will raise FC in my pool by 163 ppm. That comes out to 49 cents per ppm. I calculate the cost of each ppm of FC in my pool using liquid bleach at 79 cents ($2.57 for a 121 oz jug of 8.25%, which will raise FC by 3.5 ppm. $2.75 divided by 3.5 = $0.79). So ignoring the cost of fill water for the moment, liquid bleach is 38% more expensive than trichlor if I say away from Leslie's and use the cheapest available sources of each. If my pool averaged 1.5 ppm per day over the course of a year (not sure if that's realistic or not since this is my first year), a year's supply of chlorine (547.5 ppm) would cost $268.78 in trichlor and $432.53 in bleach. Obviously the more chlorine is needed, the greater the price difference. Now, if I had to drain and refill half the pool once a year to lower CYA that might cost about $65 more given my current water costs.
I hope I'm not banned for questioning the TFPC method. This forum is fantastic and I think it's better and stronger when a robust discussion engaging all viewpoints is permitted. As I've read lots of times on here, TFPC is science based so it ought to be able to withstand a little scrutiny from a novice like me. Actually it's not the science that bothers me- I agree that adding ONLY what the pool actually needs is the best for the pool. But I thought TFPC was supposed to be better AND cheaper AND easier. I'm just questioning the last two (yes, my testing times are getting faster but not as fast as just loading a floater dispenser with pucks once a week). I just wonder if I'm missing something because I don't see anyone else on here commenting that the TFPC method costs more and takes more time but it's worth it, etc. Maybe I'm must too much of a cheapskate.
I've checked around for better value on bleach (refillable containers at local pool store) with no luck. I'm going to keep doing TFPC with liquid bleach for now. But I think I will look into what a Pentair IC-60 SWCG would cost me. (I already have all Pentair equipment including EasyTouch automation panel). When we signed and built last year, I hadn't really discovered TFP and a saltwater pool wasn't even on our radar.
Thanks again for the collective knowledge and expertise you all so willingly share here. I've learned a ton and continue to scour the threads every day for new info, much to the annoyance of my wife =).