Algae growing during SLAM?

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alohakix

Member
Jun 28, 2019
10
Northwest FL
Hello!

I’ve been a diligent reader for the past month...once I decided we were done taking samples to the pool store and getting jerked in every direction!

The short(er) version is: New pool liner June 2019. We mistakenly (in hindsight) left the pool once full with no chemicals for a week. Pool store gave us “everything” we needed to get it back up and running. A week and a half later, took sample to pool store...FC was zero. Added a bunch of chlorine and bumped the SWG to high. Started to see some algae on the bottom/steps. Kept throwing chlorine at the pool to keep it at bay, as I had a vacation coming in July and did not want to be in the middle of a SLAM. Needless to say, after vacation, pool was cloudy and greenish. After a couple of false starts, I “officially” started the SLAM yesterday (Thursday) morning. FC levels were kept at SLAM levels for 24 hours by the time I tested this morning, yet there was still new algae growth on the bottom of the pool.

So, after 24 hours of FC levels being at 29-31, should there still be new algae growth? I’ve got a hazy blue pool that’s getting a bit clearer everyday, just thrown by the new growth! I’m continuing to brush 1-2 times/day.

Thanks for any help!!
 
Since starting SLAM:

THURS
12:15- FC 29
2:45- FC 27.5 (added 50 oz 10.5%)
8:00- did not test, just added a bump of chlorine for the night (trying to save reagents til refils get here!)

FRI
9:30- FC 26 (added 120 oz 10.5%)
1:00- FC 26 (added 160 oz 10.5%)
 
Are you brushing and vacuuming every day? Algae produces a biofilm which protects it from the elements, including chlorine. The best way to do both is, IMO, to get in the pool and do it. I can understand if it's too green and cloudy, though. Yuck!

But do brush and vac every day without fail.
 
Yes, brushing completely 1-2 times/day. And have an automatic vac in there that runs for 3 ish hours/day.

Pool isn’t too yucky. No green, just hazy blue water. The algae on the bottom was not visible until I brushed and it clouded up.
 
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I think what you are seeing is algae "carcasses". That is scientifically complete redneck but I think conveys the idea. When you kill algae it becomes visible and settles as almost dust, collecting along seams or divots in the pool floor. It is grayish, greenish, yellowish brownish (Yikes) but the KEY identifying element is it goes up into a "whoosh" when you brush it.......only to settle hours later and make it look like nothing has been done.

So, keep doing exactly what you have been doing but also tell us about your psi? has it risen? have you backwashed? Did it go back down when you did (backwash) Tell us those answers and I'll add a bit more but I think you are on the right track.
 
I suppose it could be dead? It was a brownish yellowish. It “swooshed” into a cloud once brushed. I didn’t notice any resettling, but the vacuum was running at that time.

Filter psi is my rogue factor ? I was a little over eager on the backwashing for the past 4 days. I thought backwashing would “clean” the filter and let the pool clear faster. I have since learned this is probably a bad plan, so I haven’t backwashed today. Psi sits at 19 right now and is usually around the 20 mark, although admittedly we haven’t paid super close attention, just backwashed on a semi-regular basis.

The other variable is that I decided to run the step jets and the water feature/fountain for a bit yesterday afternoon to get that high FC running through them just in case.
 
Annnnnd, I think I just found my problem. I was trying not to do another CYA test until my refills got here, but just did one anyway because of all the backwashing and hoping the level had dropped a bit. First time doing the CYA test the “right” way. It’s at 100. And I’ve been using 80. ? Draining water now to replace and hopefully get the CYA down. So upset with the pool store!!!!!
 

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If your test shows 100 it could be higher. Try dilluting it with half tap water half pool water and testing that, then multiplying the result by 2.
 
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If you could replace more than that, like 50% of the water, to get down to CYA 50, it would make your SLAM levels a lot more reasonable. You'd have to put more CYA back in when the SLAM is done for the SWG levels, though.
 
I know, just disheartening dumping all that water/chemicals. It’s 25K gal. Husband is having a hard time watching it since we literally just refilled ?. I’ll deal with whatever levels I’ve got once this is done. Just hoping it’s at least below 90 and that we don’t need to drain more. This has been the most frustrating part.
 
I'm pretty spoiled where I live. ~760 gallons from the tap is about $4.25. I had a major leak, had to replace thousands upon thousands of gallons of water, and my water bill just came in - about $50-70 higher than normal.

I understand this isn't the same experience everyone has replacing water!
 
Just updating...

Pool was full by 10pm last night. I added some chlorine (based on previous numbers...reagent refills don’t get here until Monday). Tested the water with a 5ml sample and FC was 31.

Woke this morning to clear water. Added some chlorine. Kind of flying blind until I get the refills, so my plan is just to add chlorine 3 times a day, does that sound workable? I no longer know my CYA level either, but am hoping it’s down to 80, which is what I was basing everything off of before.

Brushed the pool this morning. No new algae on the steps, which is my trouble spot. Some proofing clouds on the bottom of the shallow end, but the color was gray instead of yellow/brown/green.

Happy overall, but waiting to be able to know actual numbers, as that would make things a lot easier!!! I think I probably have enough reagent to test chlorine 2 more times, so I will do that once today and once tomorrow. Should have the new stuff by Monday.
 
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