Small, occasional bits of algae

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Kconstan

Active member
Apr 25, 2020
33
Burbank, CA
Hey everyone-

I got started earlier this year with this thread: High CYA, High Calcium, not sure what's next

Over the past week or two, I'll occasionally notice that bits of the wall in the deep end look a little yellowish. When I brush the wall, there's a bit of a cloud, though it's hard to tell if it's just scale coming off, or algae or both. After brushing, I don't notice it again for a week or so, and then I'll start to notice it again. Today, I noticed a bit on the ledge from the pool into the skimmer.

The water looks clear, I ran an OCLT test 2 weeks ago at this point to make sure I'd pass (I did), I haven't seen any CC in my nightly testing. So the question I have is, if I SLAM, how do I judge when I'm done?

I've been targeting 7 FC every evening when I add chlorine and testing daily. I'm typically seeing test results of 4.5 - 5 FC, and then I add what Pool Math tells me to add to get back to 7.

Today's test results
FC: 5.0
CC: 0.0
pH: 7.6
Temp:87
CSI: -0.17
TA: 70 (3 days ago)
CH: 230 (10 days ago)
CYA: between 30 and 40 (6 days ago)

Thanks so much for all of the knowledge I've gained so far from the forum.
 
Thanks Richard-
It’s hard to say which side is the shady side since the sun comes across the pool width-wise if that makes sense and it’s in the sun most of the day.

The skimmer ledge is definitely shaded most of the day though, and I’ve seen hints of yellow just inside the vacuum port, and in the little crevice where you’d attach a line to demarc the shallow end from the deep end. Both of those are also shady spots. I haven’t removed the light yet to see what’s back there, so I’ll update when I get a chance to check.

But there doesn’t seem much harm in treating this like mustard algae to see if it clears it.

If my goal is to keep FC at 24 (assuming I’ll treat CYA as 40) For 24 hours, is there harm in treating to, say, 26 FC to give a bit of buffer before I need to Test and treat again? I’m assuming that’s alright, but these levels are elevated from normal so I wanted to check.

Also just out of curiosity, though I suppose I'll find out the answer soon enough, does the chlorine get consumed more rapidly at higher levels than it does at normal levels? If I normally lose 2-3ppm In 24 hours at FC 7, would I expect to also only lose 2-3ppm at FC 24 during those 24 hours?

Thanks!
 
? If I normally lose 2-3ppm In 24 hours at FC 7, would I expect to also only lose 2-3ppm at FC 24 during those 24 hours
Click to expand...
Wish it worked like that but it is a percentage loss. The exact number depends on your CYA but you lose a similar percent on both those scenarios.

Like 320, I suspect mustard algae as well. Forming on the walls is the strongest indicator to me.
 
Yeah, I suspected it prior to the drain/refill in May due to high CYA, and it was/is almost like it was embedded in the calcium deposits at the time. There was definitely yellowing on the walls, and in the spots on the floor where trees block the sun for a small portion of the day. I suspect it was the cause of the mystery staining from my original post that cleared up by rubbing half a puck of tri-chlor on it. So I'm not entirely surprised, I just wasn't quite sure what to do about it since I seem to pass OCLT, clear water and no CC. Brushing everything, then 24 hours at Mustard levels seems like a good plan, and we'll go from there.

I think I'll probably hold off until Monday so that I don't close the pool for the weekend before I start, but I'll post back here when I start.

Thanks for the clarification that chlorine loss is a percentage, not an absolute value. Any risk in overshooting the target by a bit at elevated levels like this just to make sure I stay above the target?
 
Kconstan said:
Yeah, I suspected it prior to the drain/refill in May due to high CYA, and it was/is almost like it was embedded in the calcium deposits at the time. There was definitely yellowing on the walls, and in the spots on the floor where trees block the sun for a small portion of the day. I suspect it was the cause of the mystery staining from my original post that cleared up by rubbing half a puck of tri-chlor on it. So I'm not entirely surprised, I just wasn't quite sure what to do about it since I seem to pass OCLT, clear water and no CC. Brushing everything, then 24 hours at Mustard levels seems like a good plan, and we'll go from there.

I think I'll probably hold off until Monday so that I don't close the pool for the weekend before I start, but I'll post back here when I start.

Thanks for the clarification that chlorine loss is a percentage, not an absolute value. Any risk in overshooting the target by a bit at elevated levels like this just to make sure I stay above the target?
Click to expand...
Within reason, the only thing you'll damage is your wallet. If you test and it calls for 120 ounces of bleach to get to 24, I could see just dumping the whole 128 ounce jug in for the convenience factor. Targeting some outrageous number will just waste bleach, though.
 
Hey everybody. I’m about to start my 24 hour mustard algae slam. I took the light out of the niche and cleaned it out. There wasn’t much of anything in there that I could see. I found some algae looking residue in the filter basket so I scrubbed that out with a wire brush.
One question I forgot to ask. Should the pool robot be in the pool during the SLAM or should I take it out?

Tested CYA just now and I’m a bit below 30 so I’ll be targeting FC of 18-20 for what it’s worth.
Thanks!
 

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Just a quick update on the day's activities.

8:50AM: FC 18 -- Added 56oz of 10% CL to get back to 20
Brushed pool again
11:12AM: FC 18 -- Added 56oz of 10% CL to get back to 20
3:00PM: FC 12.5 -- Hopefully this doesn't screw everything up since the floor should be 18... Added 211oz of 10% CL to get back to 20.
 
Kconstan said:
Just a quick update on the day's activities.

8:50AM: FC 18 -- Added 56oz of 10% CL to get back to 20
Brushed pool again
11:12AM: FC 18 -- Added 56oz of 10% CL to get back to 20
3:00PM: FC 12.5 -- Hopefully this doesn't screw everything up since the floor should be 18... Added 211oz of 10% CL to get back to 20.
Click to expand...
You're doing fine. You'll lose quite a bit to sunlight because you're so far above normal FC/CYA levels when you're slamming. You didn't lose it all in four hours, which means you're winning against the algae.
 
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