Hi all,
24,000 gallon inground, sand filter, vinyl pool. Liquid chlorine used. No other chemicals added regularly. Hardness is around 180, pH is 7.4. FC is kept between 5 - 10 during the season.
Getting ready to close for the season (live in upstate NY, it's already in the 40's at night sometimes). A few weeks ago, I noticed some traces of mustard algae after having been on vacation for a week (I left instructions for someone to clean my pool, but in their defense, I hadn't really considered that something like this would happen on their watch). I shocked the pool and things were fine for about a week, then it reappeared.
That was about a week ago. At that point, I took more drastic steps. Double checked accuracy of my chlorine, pH, and CYA test kits against new, fresh kits. Chlorine is always fresh, I buy it from a store with very high turnover. I disinfected all equipment in a strong chlorine solution, and backwashed/rinsed the sand filter thoroughly several times. Then I added chlorine to get my level up to twice the normal SLAM shock level for my CYA of 50 - chlorine has been kept between 40 - 50 FC.
I've kept the chlorine up that high for a week now, and have been brushing the pool 2x most days (there was one day where I only did it once). I have been vacuuming about once a day (again, missed one day). Once done, the pool is 100% clean and water is 100% clear. I maintain good cleanliness throughout the season, but other than the mustard algae, this is the cleanest my pool has ever been. I vacuum with the pump on waste and hit any visible algae, then brush the whole pool. Stair rails, ladders, and toys are out for the season, so there are no hidden nooks or crannies in the pool except the returns and overflow, both of which I brush. I've had to add water from a hose twice to get the pool level back up, it's rained on other days. I've sanitized my equipment again twice during the week, and backwashed the filter twice.
Despite this, the mustard algae reappears pretty much exactly the same, every time, every day. When I go out to brush, it's always there - not a lot mind you, just a few sections where it clumps up along seams in the liner in lower-flow areas. There's usually 2 or 3 strips that are maybe 6 or 8 feet long at certain points in the pool. Far from a dire situation, but it's still there, every day, unchanging.
I'd like to totally eradicate it before shutting down for the winter. But at this point, after a week of "traditional" chlorine-based techniques and regular brushing/vacuuming, I'm stumped. It is literally doing nothing to change the growth of the algae, it comes back exactly the same, in exactly the same spots, no matter what. It hasn't slowed or reduced at all during the week.
Which gets to my question: Is there some other chemical besides chlorine I can use for something this stubborn? I know the TFP mantra seems to be "shock with chlorine until the problem goes away" but after a week with pretty much zero result, I'm starting to wonder if I've got a special situation which needs a different approach.
24,000 gallon inground, sand filter, vinyl pool. Liquid chlorine used. No other chemicals added regularly. Hardness is around 180, pH is 7.4. FC is kept between 5 - 10 during the season.
Getting ready to close for the season (live in upstate NY, it's already in the 40's at night sometimes). A few weeks ago, I noticed some traces of mustard algae after having been on vacation for a week (I left instructions for someone to clean my pool, but in their defense, I hadn't really considered that something like this would happen on their watch). I shocked the pool and things were fine for about a week, then it reappeared.
That was about a week ago. At that point, I took more drastic steps. Double checked accuracy of my chlorine, pH, and CYA test kits against new, fresh kits. Chlorine is always fresh, I buy it from a store with very high turnover. I disinfected all equipment in a strong chlorine solution, and backwashed/rinsed the sand filter thoroughly several times. Then I added chlorine to get my level up to twice the normal SLAM shock level for my CYA of 50 - chlorine has been kept between 40 - 50 FC.
I've kept the chlorine up that high for a week now, and have been brushing the pool 2x most days (there was one day where I only did it once). I have been vacuuming about once a day (again, missed one day). Once done, the pool is 100% clean and water is 100% clear. I maintain good cleanliness throughout the season, but other than the mustard algae, this is the cleanest my pool has ever been. I vacuum with the pump on waste and hit any visible algae, then brush the whole pool. Stair rails, ladders, and toys are out for the season, so there are no hidden nooks or crannies in the pool except the returns and overflow, both of which I brush. I've had to add water from a hose twice to get the pool level back up, it's rained on other days. I've sanitized my equipment again twice during the week, and backwashed the filter twice.
Despite this, the mustard algae reappears pretty much exactly the same, every time, every day. When I go out to brush, it's always there - not a lot mind you, just a few sections where it clumps up along seams in the liner in lower-flow areas. There's usually 2 or 3 strips that are maybe 6 or 8 feet long at certain points in the pool. Far from a dire situation, but it's still there, every day, unchanging.
I'd like to totally eradicate it before shutting down for the winter. But at this point, after a week of "traditional" chlorine-based techniques and regular brushing/vacuuming, I'm stumped. It is literally doing nothing to change the growth of the algae, it comes back exactly the same, in exactly the same spots, no matter what. It hasn't slowed or reduced at all during the week.
Which gets to my question: Is there some other chemical besides chlorine I can use for something this stubborn? I know the TFP mantra seems to be "shock with chlorine until the problem goes away" but after a week with pretty much zero result, I'm starting to wonder if I've got a special situation which needs a different approach.
