Yellow algae won't go away!

mgtfp

Bronze Supporter
Mar 5, 2020
386
Melbourne, Australia
I don't think it really matters when you vacuum the dead algae out. The most important bit is to keep brushing, and to maintain the MA SLAM level for 24h hours.

I think most people don't really see much more algae after passing the normal SLAM. The 24h at MA SLAM level are really only to finish it off.

Your case does look unusual...
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Free Chlorine 33 ppm and Combined Chlorines Zero this morning at 9AM. Very overcast today...maybe some FC loss due to sunlight and a couple of rain squalls overnight but I had the pool at MA SLAM FC level 41 ppm at 4:30 PM yesterday.
 
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The one and only time I dealt with algae I used the SLAM process but it kept coming back. I realized there was a reservoir of algae somewhere that wasn’t being reached by the chlorine. It took quite a while and lots of investigating to find it. I started with the light niches and ran the slam with them open. I eventually tracked it down to an auto fill I had disabled by shutting off the fill valve (long story). Plugging the fill tube at the pool solved the problem.
 
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Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Vacuumed algae off the bottom to waste, deep cleaned and brushed pool and niche. Added 125 oz. per pool math and FC now measures 38.5 ppm/CC 0 ppm. Going to leave it at this level for the rest of the day and see if any growth begins before bedtime tonight!

Sure hope this is it.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Had an think on alternate sources while cleaning the pool...

Has anyone had plant debris cause algae? We have two ferns inside the screen and wife wants to keep them for aesthetics. I hate them because they constantly lose little leaves and litter the pool. Usually they stay on top but I wonder if they might bring spores into the pool?
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Big cell came through. Our pool area flooded and spouse and I had to push deck water into the pool. I vacuumed again to take the small dirt debris off the bottom and just now checked the Chlorine. FC 38.5. same as four hours ago and zero CC.

Mustard algae has returned! See picture below. This is how it starts, in a small indentation in the vinyl floor and in the deep end. There's another couple of small spots... the one in the picture is probably 3 inches long.
How can anything live in this level of Chlorine? I'll probably bring it up another 5-10 ppm or so to reach the MA SLAM numbers for higher CYA. 90 CYA is 52 ppm, probably another gallon of Bleach.

______________
I thought of one possible source near the skimmer lid that I'm working on eliminating. We have two holes in the concrete for a volleyball net maybe 5 inches from the lip of the pool. One is very close to the skimmer lid. It is almost always full of water and eventually evaporates but I got all the water out of the skimmer side one, cleaned out the 2 inches of nasty crud in there and filled the hole with straight bleach. Just letting it sit now. When I stuck a rag down there the water came out and went straight down into the skimmer lid area so it's a possibility but now eliminated. I'll do the other side as well just in case.
 

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Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Just added 201 oz. more 11% Bleach... Should get me to 52 ppm or thereabouts. More thunder on the horizon... a lot of instability in the Gulf of Mexico right now due to Tropical Storm/Hurricane Hanna making it's landfall near Galveston/Houston, TX
 

mgtfp

Bronze Supporter
Mar 5, 2020
386
Melbourne, Australia
I find it hard to believe that any algae could not just survive, but apparently thrive at these FC levels. Unless your are massively underestimating your CYA. But the answer shouldn't be to go way beyond MA SLAM level. Some people who stayed long periods at MA SLAM level reported bleached vinyl liners. Your equipment may suffer at these levels.

You need to verify your CYA-level.

How do you measure your CYA? And how did you reduce your CYA from 110 to 70?

Could all this stuff just be debris that gets washed into the pool during these storms you are reporting? Is the stuff in the photos attached to the surfaces, does it need brushing to come off, or can you just vacuum it out?
 
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Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Measured CYA with two methods. Taylor test in TF100 kit and Pentair stand alone “Rainbow” test kit.
Taylor showed 65-70, Pentair 90 ppm before I raised the SLAM chlorine amount.

I reduced CYA by draining roughly 1/3rd of my pool and refilling with city water. It was dropping from 110 to 100 due to on recent Heavy rains over the past few weeks. (All previous tests until this week were done With the Pentair kit, it’s quite easy but takes much more reagent than the Taylor).

Some of what’s on the bottom might be debris but it clearly changes color from mustard yellow to dark brown at some point. Plus, we’ve never seen this yellow algae before. We’ve had green algae in the past but only rarely, maybe once annually.

Typically, the yellow algae starts small...Like tiny “dots,” then those coalesce into a blob-like form after a few hours of growth. Later, over 6-12 hours, the chlorine in the water kills it and I vacuum it up. It doesn’t move, it must be brushed or vacuumed....and is almost always in the same or close to the places.

BTW, the dichlor pucks have already bleached the liner pretty bad below the waterline. I’m going to keep this level as long as I can to kill this outbreak.

Did a full bottom and sides brushing before I turned In tonight. If anything was growing on the bottom it’s in the Chlorinated water now.
 

Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Backwashed today for three minutes, rinsed then another backwash for two minutes and final rinse.

ive been contemplating a deep clean of the sand filter but the water is super clear in the sight glass during backwash and rinse...
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
1,473
Spring Valley, NY
I find the sight glass to be worthless. They really don't show what I visually see at the end of a backwash hose. I will put a filter into backwash and then run to the other end very quickly to watch the garbage make it way out. It starts off rather looking not bad and then all of a sudden the dirty water makes its way. When thats over the water right at the hose end will have a white frothy look to it. At that point I go another half to 1 minute followed by a 15 second rinse and consider it done.
 
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Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
First day without yellow algae In almost a week!! Fingers crossed. No chlorine today... FC 41, CC zero mid day today. Pool looks great. Going to let the FC alone and turn down the pump to super low and let any solids fall to bottom overnight. I’ll vacuum tomorrow.
 

red-beard

Gold Supporter
May 27, 2019
494
Houston, TX
I fought Mustard Algae for several years. The issue was very high CYA. I used the stupid Tri-Chlor pucks. I used them for about 10 years straight without draining. I drained the last few years, but for one reason or another, the CYA became too high (because I kept using the stupid pucks!!!). I drained the pool again this year and started over with the EXACT TFP methods.

This year I finally have it under control. I have my CYA at 30. This is high enough to have decent retention but low enough that that the Chlorine is extremely effective. This is the only part where I deviate from the site wisdom.

I use only Cal Hypo 73% (to get my CH up) and now 10% Home Depot Bleach. I raise my FC to 6 ppm every night and I keep my pH under 7.9 (adjusting to 7.7 when it reaches 7.9). With the FC this high (for my CYA), it will stay like this over night, being extremely effective. I usually drop about 2-3 ppm FC during the day. After the direct sunlight is off my pool, I test and then adjust FC after the nightly swim.

I am now reaching 2 months without a mustard outbreak. Seems like a miracle.

I suggest you drain/refill to get your water to 30 ppm, do a SLAM and then follow my nightly method.
 
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Macysumo

Silver Supporter
Jun 27, 2020
37
Pensacola Florida
Wife is getting frustrated too... thinks I'm an idiot doing the pool maintenance myself. I'm an engineer so I have some ability to follow a process :)
Says " take a sample to the pool store" and buy some yellow algae killer (a local neighborhood web app poster said "that works for his pool").

Okay, today's update... First, I didn't add any Bleach last night. Just left the pump on low speed (800 rpm) to see if I could get any debris to the bottom.
Yellow mustard in mostly the usual places starting around 9 AM (not before).

Big rain storm this morning and had to pump some water to waste from the pool. Otherwise I didn't touch the pool, totally bummed this stuff keeps coming back. Have no idea what the source might be.

2:45PM Readings:

FC 28, CC 0, CYA 50 (Taylor), 70 (Pentair),pH 7.2
Added 1 lb of pH plus... pH stable after one hour at 7.6