First of all, thanks to all of you for the great advice I've received so far. This is my first pool and I'm a little over a week out from the initial fill. All things considered, putting the knowledge I've gained here into practice, my first few days have gone very smoothly.
I'm curious as to how efficient SWGs are. I ask because of what's happened the last couple of days.
Oklahoma is usually hot and dry this time of year. This summer has been odd however, and the last 3 days have been overcast, with moderate to heavy rain on 2 of them.
My pool contractor set our SWG on an initial schedule of running 8a-5p with the SWG set at 65%.
When I'd last done a FAS-DPD chlorine test (last weekend), I had FC of 7 with CC of <.5. I was pleased and had hoped the sun would help me get and keep it down to my current target of about 5 ppm while I am working at dissolving some CYA in the water. My final target is the lower end of the CYA/FC chart. I'm going for 60 CYA and 5 FC.
Fast forward to this week. It rained all day Wednesday and Thursday. Nobody swam and there was no sun. The pump and SWG still ran on the 8-5, 65% schedule. I came home last night to find a large amount of red dirt in the pool. With the pool build just complete, I'm not able to lay sod until tomorrow morning. The rain had splashed a lot of mud onto the decking, then into the pool. To top it off, we'd had enough rain that we'd probably gained 3 inches on the water level.
I spent about 90 minutes vacuuming the mud and skimming the leaves. It cleaned up surprisingly well (and quickly) for everything that was in there.
I took an OTO test for chlorine and pH expecting the worst. I figured between the mud runoff into the pool, the dilution, and the trees near our pool that had also dripped a bunch of water off their branches, I was looking at low chlorine and potentially some evil growth. But the OTO test showed a darker yellow than I'd seen so far.
So I broke out the FAS-DPD test, figuring there may be a lot of chlorine in there, but it's likely that all the mud and debris was going to leave me with a high CC.
Last night's test,
FC - 15.5
CC - still less than .5
So good news and bad. I am way too high on my FC, but it looks like I got the mud out before it caused a problem.
Everything I've read here makes me think that a combination of the SWG running 9 hours each day on the cloudy days PLUS the rainy, overcast weather, combined with the fact that I have now dissolved a total of about 3# of CYA into my system, contributed to the pool not just holding, but increasing FC. I don't know my CYA level yet. I added the largest dose (2#) on Monday of this week and was going to wait until the end of the weekend to test for it.
Does the logic on the high chlorine sound about right?
For what it's worth, it's still a little overcast this morning, but should clear up later in the day. So I set the pump/SWG to run only from noon to 2 pm. I was going to run a more abbreviated schedule until the sun returns consistently over the weekend. Even then, I will still likely start ramping down from the 9-hour schedule my contractor has it on. I'll probably leave it on 65%, but knock an hour off every couple of days until my FC is holding in the 5 ppm range. Then I'll resume CYA additions until I can get it to 60.