Should I SLAM??

[mavitia22]

Hello. I need y'alls opinion on whether I should do a SLAM.

Last night at 8:30 pm when my pump shut off, I went to clean out the basket and saw what I thought was the start of algae on the ledge (a few inches below the waterline) of my fiberglass pool. It was only along one corner, so I brushed it off. I immediately tested chlorine so I could do an OCLT.
FC - 5
CC - 0
Morning Tests:
FC - 4.8
CC - 0
(I used 25 mL sample cuz I wanted the most accurate result)

This morning, I turned SWG to 100% output since I wasn't going to be home all day and wouldn't be able to get LC until this afternoon. I tested FC again at 2 pm today and it was 6 ppm, CC-0. I looked all around the pool, no sign of green on the ledges or anywhere else. I vacuumed to prepare for SLAM, and no sign of algae in the Dolphin. So, water is clear, passed OCLT, no combined chlorine....but I know there was something last night. When I wiped it with a white paper towel, it was yellow-green. So, mustard algae or pollen?

I don't think pollen would settle on the ledge like that in just one area, as I've read here in other threads. Plus, it's an area with little circulation. But, even after all night and day, I didn't see anything resettle in that spot, or anywhere else. I thought mustard algae keeps coming back to the same spot?

So, question is...do I SLAM?? Right now, since it's evening, and things look clear, I'm going to do another OCLT, just to double check. But if I pass tomorrow morning, and still not see any visible algae, should I trust that? I want to avoid a SLAM if I don't need it, but if you guys think I should, then I will. Help!
Today's Results:
FC - 6 (had been consistently 4 lately and last night 5, will test again tonight)
CC- 0
TA-60
PH - 7.8
CH- 160
CYA - ?? ( At 50 dot was visible, at 40 semi-visible, at 30 not visible...so is it 40???)
Salt -Taylor 2800 ( SWG -3100)
Temp - 94

 

[drsipe]

Hopefully more people will chime in, in my perspective, the end of a SLAM requires three conditions.

1. The water is clear
2. Combined chlorine of 0.5 or less
3. Pass an over night chlorine loss test

If you already meet all three criteria, I don't think a SLAM is needed. With that said, your CYA is low (target 70 - 80), the low CYA allows the UV light to deplete your chlorine, along with that, your chlorine level is on the lower side of target, especially with your water temps, you want to maintain at the higher end of the target range.

 

[mavitia22]

Hopefully more people will chime in, in my perspective, the end of a SLAM requires three conditions.

1. The water is clear
2. Combined chlorine of 0.5 or less
3. Pass an over night chlorine loss test

If you already meet all three criteria, I don't think a SLAM is needed. With that said, your CYA is low (target 70 - 80), the low CYA allows the UV light to deplete your chlorine, along with that, your chlorine level is on the lower side of target, especially with your water temps, you want to maintain at the higher end of the target range.
View attachment 522938

Ok, thank you. Yes, I hope others do chime in.
I did recently add stabilizer, then a few days later we had to pump water out because we accidentally left the hose on all day. So, that messed with the levels I guess. But now I'm waiting on this "algae" issue to pass, just in case I do have to SLAM I'll be at a lower CYA.

 

[Mdragger88]

Visible algae trumps the oclt.
If it were me I’d raise to slam level then do the oclt.
Count your cya as 40 (cuz you’re inbetween 30&40 - which is low for a swcg pool by the way. Once you pass another oclt & don’t see a reoccurrence anywhere (all clear) or complete the
SLAM Process
you should bump that up.
FC/CYA Levels

Mustard algae likes shady spots but it can be anywhere- doesn’t necessarily only return to the same spot.

 

[Newdude]

Visible algae trumps the oclt.

Its gone now.

Technically there's no current need to SLAM, but I'm always on team : SLAM first ask questions later.

If you SLAM when it wasn't warranted, it's over the next morning. The peace of mind is worth it IMO.

 

[mavitia22]

Visible algae trumps the oclt.
If it were me I’d raise to slam level then do the oclt.
Count your cya as 40 (cuz you’re inbetween 30&40 - which is low for a swcg pool by the way. Once you pass another oclt & don’t see a reoccurrence anywhere (all clear) or complete the
SLAM Process
you should bump that up.
FC/CYA Levels

Mustard algae likes shady spots but it can be anywhere- doesn’t necessarily only return to the same spot.

Ok, will do.

 

[Mdragger88]

Ok, will do.

Hopefully it will be very quick but it should give you some peace of mind that its taken care of.

 

[mavitia22]

Its gone now.

Technically there's no current need to SLAM, but I'm always on team : SLAM first ask questions later.

If you SLAM when it wasn't warranted, it's over the next morning. The peace of mind is worth it IMO.

Yes, need peace of mind. Thanks!

Hopefully it will be very quick but it should give you some peace of mind that its taken care of.

Ok, so last night, I was so eager to bring up to SLAM level, that I threw in a gallon of LC. It raised FC to 15, but I completely forgot about PH. I know I'm supposed to lower it for a SLAM. It was 7.8 yesterday. Will high PH affect the chlorine's effectiveness? Can I add acid with a high level FC?

 

[Newdude]

Can I add acid with a high level FC?

You shouldn't. What's done is done now. Hopefully the SLAM is over quick and it doesn't matter.