Tailing off a SLAM, but missed readings on critical day

[jbailey895]

So I started my SLAM on Monday, and had fairly consistent results, with no overnight losses on Wed, Thurs I didn't get readings at all, and now its Fri (Day 5) and my FC level has dipped from 22 to 17, water looks good with no perceptible algae. My readings today:

17 FC
0 CC
500 CH
140 TA
7.8 PH

I know PH will be off during SLAM, I guess the only question is whether the loss of 5 FC over more than a 24 hr period is a concern; should I bump back up to 20, or let it come down gradually and assume I'm OK? The more precise way is to bring it to 20 and do another OCLT tonight/tomorrow, but thought I'd check in with the experts. . . .

TIA,
Joel

 

[Mr Bruce]

That is completely normal, especially if it's been sunny there the past 2 days.

What's your CYA?

 

[woodyp]

Assume nothing when you've got this much time and effort in. Bump it back up and perform ANOTHER OCLT.

 

[jbailey895]

Thanks guys, I started at 50 CYA (it was between 40-50) and its SWG. OK, I'm close enough to 20 anyway, might as well do it right. how soon after adding can I check? I'll use pool math to add the appropriate bleach.

 

[Mr Bruce]

The OCTL doesn't require you to bump your FC to SLAM levels. If you wanted to do another one overnight you could just start with what you have, 15 or whatever. You just don't want to start with something low, like 3.

If you passed Wednesday night, have crystal clear water and have CC <= 0.5 there is no real point in doing it AGAIN. 2.5 loss of FC / day is completely normal.

Your CYA should also be bumped up now for your SWG.

 

[jbailey895]

OK, I'm a bad pool owner. Didn't get post-sundown readings again last night, and readings today:
13 FC
0 CC
625 CH (?)
120 TA
40 CYA
8.2 ph

Water looks clean, no visible algae. I cut the lawn near the pool on Thurs, and there is some residual debris on surface from that, but otherwise looks good. (pump only ran about 6 hrs since I wasn't home to turn it back on too) Not sure why the ph went up, and TA went down. I'm going to raise the CYA with a sock and dump some MA to get the ph down, but won't be able to do an OCLT tonight either, anyone think I should bump the FC back up for another day, or just continue to fall off since no CC's?