Now you can make note of that clean filter pressure. Once it increases by about 25%, that means it's dirty and time to clean them off again.
As for your FC level and stuff, I want to re-cap to ensure you have a good handle on things there.
1 - We are going to assume your new CYA is 50 based on this morning's results.
2 - Now that you have a good CYA, always go back to the
FC/CYA Levels. There you look at the top chart (non-salt pool), find your current CYA, and see what your FC "should" be. Never let it fall below that minimum number or you run the risk of cloudiness and algae - especially once our water temps go back up.
3 - When you determine your FC may be low, go to the
PoolMath tool or app. There you can see how much bleach (make sure you use the right percentage) is required to increase however many ppm needed. EXAMPLE: Using
PoolMath, I see that two gallons of 10% bleach/chlorine should increase your FC by just over 7 ppm. You should not always need to add that much, but if your FC was zero this morning, something is not right. So add the bleach right away, then consider testing again in about an hour to see what it's at. The FC should hold fairly steady. Ideally, you never want to lose more than 4 ppm of FC in 24 hours.
4 - As for the FC testing, you never need all those scoops of powder. Do your FC testing as follows: Use the 10 ml water sample and add
ONE generous/heaping scoop of powder. That's it. It should turn Barbie pink right away. If not, you have NO chlorine and need to add some ASAP. Now after you add the scoop of powder, mix and add the R-0871 drops one at a time until it goes clear. Whatever number you get, divide by 2 and that's your FC. (i.e. 8 drops from pink to clear = and FC of 4). Once you have that FC number, go back to the
FC/CYA Levels and increase the FC as needed.
Because your FC dropped to nothing, perhaps more than once, I'm concerned about cloudiness and algae. If you see that let us know. But if the water is still crystal clear, I would increase the FC to about 8-10 for today. It's safe. But your water needs sanitation now before things get away from you. After that, if your water retains FC better, then maintain the proper FC as noted on the
FC/CYA Levels.
Let us know if you have more questions.
You can see how off their CYA test was to yours. Always go with YOUR testing. We generally don't like to waste chemicals just to dump it right out onto the lawn, but in your case, that FC is low. Your saving grace right now may be fairly cool water and the weather systems flowing across our state. If this was summer, your pool might be green with FC that low. So if you are going to drain some water, do it ASAP and replenish the FC right away. If you don't exchange water soon, still make sure to increase the FC right away. Use regular bleach or pool chlorine (same thing). Make sure the bleach is plain - never use splashless, scented, or Clorox/Cloromax products. The stabilizer should never go up again as long as you stay away from tabs & pool store bags of shock. You are in control to later increase CYA only when needed - later.
We'll look for updates tomorrow with a fresh set of eyes. 