Did a SLAM, might be ok but not sure

[Bart]

I'm only at my pool on weekends so my data is going to be a bit spread out.

Last Friday night I tested and the FC was zero. I dumped a few gallons of bleach in and went to bed. When I pulled the cover off the next day, the water was cloudy and there was a tiny bit of noticeable algae, so I dumped more bleach in and ran the pump 24 hours. By Sunday big improvements were noticed and I backwashed.

On Monday I actually read the SLAM method (!) and only then realized I needed to bring my FC way up to 24 to do it right. So I went back out on Monday night and added the proper amount of bleach (12 128 oz jugs). At this point the pool looked great but I wanted to be totally sure. I turned the SWG up to 70 which is higher than normal left.

I went back up on Wednesday night to check it and the FC had dropped to 8 from about 14 (don't remember the exact value, but it was high). To me this seemed to make sense - the bleach shock was wearing off and presumably the SWG was working. (Does that make sense!?!??!)

When I got up here last night (Friday), the water looked good and the FC was 4.

I did an OCLT and this morning the FC is 3

Everything looks great, right???

My only concern is with the "low" FC level last night. With the SWG at 70 I was expecting the FC to be higher (last year, running at 40 or 45 would usually give me an FC of 4). Am I being paranoid or is something weird going on here?

Other info: pool is covered all week with a floating cover, no one swam in it all week, CYA is 70, pH is 7.2, temp is about 90


So what do you think?
1. Is my SWG cell dead (no error codes or warning lights are on)
2. Shouldn't the FC value be higher?
3. Am I just paranoid?
4. What should my next step be?

Thanks!!
Bart

 

[Smykowski]

Everything you are describing sounds normal given the cloudiness and visible algae. The FC is doing its job, you're just not replenishing it fast enough. SWGs can maintain FC in a clean pool, but they will not be able to keep up in a dirty pool.

You should be testing and dosing as often as required to maintain an FC of 24 at all times. This might mean testing every hour or two at first.

The SLAM is not a once or twice application of bleach. It is "raise FC to Shock Level And Maintain" it there.

 

[Bart]

Thanks!

When you say "maintain it there" how long are you talking about?

 

[Smykowski]

As long as it takes to pass the three criteria in the SLAM article. We've seen some take a couple days, and some take a couple weeks.

 

[Bart]

But based on what I said above, I think I've already passed:

Clear water
OCLT from 4 to 3
And I've never had any CCs

Are you saying that since my SWG set at a higher than normal rate isn't giving me what I expect that my SLAMing is not actually complete?

Thanks

 

[Patrick_B]

Not necessarily, but it could be. You aren't running the SWG overnight are you?

 

[jblizzle]

I would be more comfortable saying you passed the OCLT if you started your FC closer to slam level and not so low.

 

[Bart]

Nope, I only run it during the day when the pump is on.

 

[jblizzle]

I prefer the pump to be running 24/7 for the SLAM process and for the OCLT.

 

[Bart]

I would be more comfortable saying you passed the OCLT if you started your FC closer to slam level and not so low.

Thanks!

I just re-SLAMed. I'll do another OCLT tonight/tomorrow and post the results.

Will it still be meaningful if my level goes from say 18 to 17 or is that too high of a starting point to be valid?

 

[Bart]

I prefer the pump to be running 24/7 for the SLAM process and for the OCLT.

Ahhh. I'll keep it going tonight and I'll turn off the SWG at the normal time.