Interesting read...
I feel it's important to point out that a single 24 hour period FC loss does not mean that's all your pool will lose on other days. Additionally, there's a possibility of testing error being a factor (happens to all of us). You would have to test your water for a week or more to actually know what your average losses are daily. The general rule of thumb is 2-4ppm, or roughly ~50% of your FC is lost daily, not accounting for other factors such as swimmers or environmental changes (rain, dust, clouds, etc.).
This is EXACTLY what I discovered just now, when I tested, 24 hours after seeing a 2.5ppm loss in the first 24 hour period. What I saw today was an 8ppm loss over the 2nd 24 hour period! In fact, I was just getting back on here to post a question as to what might cause this, aside from testing error (more on that below), when I saw your post. The good news is that the remant patches on the plaster that have been brushed daily since starting this endeavor 3 days ago(?) are almost all gone. This fact, combined with the nearly triple FC loss I just recorded, along with your post and what someone else previously said, leads me to believe that such a big FC loss today could be partly contributed to the recent sustained higher FC level indeed being effective at killing off the algae in my pool, thus the consumption of much more FC than the first day. Granted, this assumption is based purely on what I can see, and this theory may not hold water (pun intended). That said, even if this theory is correct, this doesn't mean that I am inclined not to SLAM.
If you do decide to SLAM, I feel like it might be difficult to convince you that you'll need to maintain that SLAM FC level by testing and adding chlorine 3-4 or more times daily. As a precursor to that discussion... your SLAM will be less effective and slower (take far more time) if you try to skimp on that part. Conversely, it will be shorter and more effective if you do test and add chlorine back to SLAM level 3-4 or more times per day.
Au contraire, when I do SLAM, I will maintain that SLAM FC level as best I can, but will likely only be able to add LC twice a day.
You can safely swim at or below SLAM level for your CYA.
All the more reason to ensure CYA is properly tested.
Speaking of which, I was actually wondering earlier if it was possble that my CYA test results were wrong, which might explain why I am seeing such good (in my eyes) results with the algae thus far. I doubt I erred, though, because I did the regular test first, which prompted me to subsequently do the diluted test, so I had to have been wrong twice in quick succession. To clarify, the normal test resulted in the cloudy water not even getting up to the 100 mark, and it was shy by a considerable amount. However, when I did the diluted test, it hit 50 on the nose, which indicates my level is supposedly 100. If I was wrong (first time I ever hoped I was) in my test, and my CYA is really more like 30, then I would be slamming at the levels I have been trying to keep thus far. But, that's a far reach, especially since I've been running the trichlor pucks for so darned long.
I realize that it doesn't rain often in your area, but you may want to consider rain collectors on your downspouts to try to collect as much free water as you can get. Maybe you can get your neighbors to collect it for you too. Invite them to swim more often maybe?
Nice thougt here, but wouldn't downspout water be too dirty to put in a pool? I have a tile roof and when I clean my gutters I see all kind of sand from the erosion of the tile in the gutters, not to mention leaves and all that. Or, is that OK, as long as that stuff isn't swimming in the water column?
While we don't have rain often, when we get it, it's BIG! I live in the foothiils right above a big lake, and the storm clouds come across the lake and park at the hills and just preciptate water out of the lake and dump them on my house. I can drive 5 miles down the hill or even just across the lake, and it will be sunny, but when I look toward my house it's black and you can't even see the hillside. So, I'm trying to live with the high CYA for the next few months. Of course, I may lose patience along the way. ;-)
... I meant that so much of your CL is bound up with the high CYA you have to maintain a higher CL level for it to be effective. and its easier to let it slip... in case you haven't seen this chart.. it gets called out all the time: FC/CYA Levels
