I just finished a 10 day SLAM on my 7500 gal above ground pool to eradicate some mustard algae I've apparently had since the beginning of the season (always thought it was sand from the filter or pollen). I had to go as far as 12 gallons of liquid chlorine, about 8 bags of granulated shock, and eventually succumbed and used a pound of ammonia based Yellow Out which was the only thing that actually cleared the problem. I've read that the spores for this algae sticks to everything that's contacted the water so I've soaked my tools and vacuum for a good part of the SLAM and I've double washed my towels and bathing suits. The algae was only ever on the floor of the pool, never saw any coming off when brushing the sides. I certainly don't want to go through this again, so how can I thoroughly sanitize my solar cover? Or am I ok to just start using it again? My FC is still a bit high (about 8 or 9 ppm with 70ish CYA, 0 CC, 7.4 pH) but I'm sick of not having my backyard joy so I'm typing this from inside the pool right now!
Mustard algae and solar cover?
- Thread starter bwaredapenguin
- Start date
- Jun 22, 2014
- 52,053
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Welcome to TFP! 
Aside from any concerns about how you may have managed the previous algae and/or Mustard Algae situation, the cover itself could get tricky. Do you have a way to pull it backwards (bottom side up) to clean it and perhaps let the sun hit it? I'd like to see what others have to offer on this matter as well as your options may be somewhat limited. 
www.troublefreepool.com
www.troublefreepool.com
Pool Care Basics
Aside from any concerns about how you may have managed the previous algae and/or Mustard Algae situation, the cover itself could get tricky. Do you have a way to pull it backwards (bottom side up) to clean it and perhaps let the sun hit it? I'd like to see what others have to offer on this matter as well as your options may be somewhat limited.
Mustard Algae
Today We are going to show you how you can get rid of mustard algae in your pool. By following the steps in this guide and with no expensive chemicals.
www.troublefreepool.com
SLAM - Shock Level and Maintain
We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.
www.troublefreepool.com
Pool Care Basics
It's not on a roller or anything so I can pull it off and lay it out in the grass, but besides spraying it down with a hose I'm not sure what other viable options I have to both clean it and not ruin my lawn.
- Jun 22, 2014
- 52,053
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
@JoyfulNoise do you think a diluted chlorine-to-water ratio is safe for the cover yet still effective to clean a cover that was over a suspected Mustard Algae pool? Is it even worth trying, or is exposure to the sun's UV adequate enough to kill residual spores?
- Jun 1, 2018
- 16,050
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Your fc is currently in target
range for your cya of 70 - its not high FC/CYA LevelsDid u follow the SLAM Process to completion maintaining 28ppm fc & meeting all 3 end of slam criteria before moving on to MA slam level (40ppm) for 24 hrs as listed in the MA article?
If so there was no need for the yellow out. I fear now you will be having to overcome the ammonia in the yellow out. How much did u use?
How are u testing the water?
As for the cover, can u take it to the driveway? A 50:50 bleach/water solution & some scrubbing should do the trick, so long as you rinse the area well there should be no ill effects on the grass. You can always wet the grass 1st too to protect it. Thats what power washers/house washers do before using bleach mixes.
Followed the SLAM instructions and used the tfp calculator app, took it to 50+ out of frustration and some still returned, that's when I went to 1 lb of Yellow Out followed by a full gallon of 10% liquid chlorine 5 min later, 12 hours later, then a quarter to half gallon 12 hours after that. Haven't seen a hint of it since then so I'm not really worried about that recurring unless I reintroduce it. I don't think the ammonia solution should be a problem since the chlorine shock converts it to an inorganic chloramine and any remaining keeps up eating the chlorine until it's gone. I'm staying rock solid at FC levels with 0 CC even after a storm yesterday that dumped 0.8" of rain and threw in a bunch of leaves and pine straw.
As far as testing I'm using the K2005 kit and was using mostly the 1.8mL dilution level with tap water to take it to 9mL during the SLAM. As far as CYA, depending on what's actually meant by "the dot disappears" it could have been anywhere from 60-80 so I was erring on the side of caution for return to use with saying it might be on the higher side.
I could consider the driveway but that'll certainly be a bit of a pain since it's nowhere near 18' wide! Is 50:50 the max dilution you'd recommend for this? Speaking of pressure washers, I do have one. Maybe instead of scrubbing I could use the 40° tip at a decent distance with some diluted bleach to avoid the annoying scrubbing part. I feel like scrubbing will likely just rip the bubbles apart.
As far as testing I'm using the K2005 kit and was using mostly the 1.8mL dilution level with tap water to take it to 9mL during the SLAM. As far as CYA, depending on what's actually meant by "the dot disappears" it could have been anywhere from 60-80 so I was erring on the side of caution for return to use with saying it might be on the higher side.
I could consider the driveway but that'll certainly be a bit of a pain since it's nowhere near 18' wide! Is 50:50 the max dilution you'd recommend for this? Speaking of pressure washers, I do have one. Maybe instead of scrubbing I could use the 40° tip at a decent distance with some diluted bleach to avoid the annoying scrubbing part. I feel like scrubbing will likely just rip the bubbles apart.
- Jun 1, 2018
- 16,050
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
So long as none of the bubbles have popped the sprayer may work. Let the bleach mix dwell a little bit but don’t let it dry! Maybe 5 minutes.
Solar covers usually only last a season or two so if it’s a couple yrs old & showing signs of wear u may just wanna replace it.
Definitely watch your fc & keep it up. You may even consider maintaining MA minimum for a while if u are sure u had MA. 10.5ppm for cya of 70.
How do u chlorinate your pool? Your cya is a bit high if you don’t use a swg.
Solar covers usually only last a season or two so if it’s a couple yrs old & showing signs of wear u may just wanna replace it.
Definitely watch your fc & keep it up. You may even consider maintaining MA minimum for a while if u are sure u had MA. 10.5ppm for cya of 70.
How do u chlorinate your pool? Your cya is a bit high if you don’t use a swg.
First season of this pool and solar cover (tore down rusted out 15' SWG over the winter) so I definitely don't want to trash the cover yet. I'll keep my chlorine around this level for a while. The CYA is mostly a result of me being an idiot and trusting test strips back in April after filling it which led to me adding way too much stabilizer. I've drained/refilled as much as I'm willing to for this season. For chlorine I am using trichlor pucks in addition to either no CYA granulated shock or more recently liquid chlorine. I think I'm gonna stick with liquid for the shock since I can get more bang for my buck there. Thanks for the advice on the solar cover, I think I'll deal with that tomorrow. Definitely will be keeping a fastidious eye on the levels daily for a bit until I feel totally comfortable that things are back in order. Luckily with my climate I get to enjoy the pool into October so I've got plenty of time to make up for the 10 days it was out of the equation!
Could you perhaps offer a little guidance on the CYA test? It's 80 if I'm considering it "invisible unless you're actively looking for it" and 60 if it's supposed to be truly invisible without a hint that a black dot was there.
- Jun 1, 2018
- 16,050
- Pool Size
- 26000
- Surface
- Vinyl
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
It should be mostly obscured (mostly invisible) with a glance - no staring. Example- If that occurs inbetween 70 & 80 u call it 80. Always round up if inbetween.
The pucks are only adding to your cya issue therefore setting the bar for the necessary minimum fc level higher each day.
It’s hard to hit a moving target.
Here’s what each dissolved 3” trichlor puck does to your water
This doesn’t take in to account the copper that is often added to pucks with “blue” in the name which can cause staining of surfaces, turn hair, fingernails, & even the water green if the level gets too high.
I suggest your pool goes on the liquid diet exclusively.
The pucks are only adding to your cya issue therefore setting the bar for the necessary minimum fc level higher each day.
It’s hard to hit a moving target.
Here’s what each dissolved 3” trichlor puck does to your water
This doesn’t take in to account the copper that is often added to pucks with “blue” in the name which can cause staining of surfaces, turn hair, fingernails, & even the water green if the level gets too high.
I suggest your pool goes on the liquid diet exclusively.
Thanks! I am mostly sticking with liquid now especially since I have a bunch left after the slam. We've gotten a fair bit of rain recently (at least 5" since last checking in) and tested the CYA today and it was about 65 with a stare (did it before catching up here) so I'll stick with saying up to 80 for now. Definitely not interested in draining/refilling 5/8 of the pool especially at this point in the season so I'm going to ride out the CYA level and appropriate FC to match. I may add in a SWG next spring and if I do I believe this is an appropriate CYA level for that, so there's that too.It should be mostly obscured (mostly invisible) with a glance - no staring. Example- If that occurs inbetween 70 & 80 u call it 80. Always round up if inbetween.
The pucks are only adding to your cya issue therefore setting the bar for the necessary minimum fc level higher each day.
It’s hard to hit a moving target.
Here’s what each dissolved 3” trichlor puck does to your water
View attachment 446261
This doesn’t take in to account the copper that is often added to pucks with “blue” in the name which can cause staining of surfaces, turn hair, fingernails, & even the water green if the level gets too high.
I suggest your pool goes on the liquid diet exclusively.
The good news is I did clean the solar cover and have used it since and all my levels are staying ROCK SOLID! I decided to take a few buckets of pool water and saturated the cover while stretched out on the grass, after a couple hours in the sun I rinsed it down with a hose and allowed it to bake bone dry before flipping it and doing the same to the other side the next day.
Only thing I've needed to do since my last comment was that I added 6-10oz of liquid 10% chlorine a few nights ago due to the mildest perceptible difference when adding the total chlorine reagent, but at this point I feel the mustard incident is fully resolved and no ill effects of having used the Yellow Out.