I am new to this forum and seeking advice on a couple of issues with my indoor pool. They might be related but I'm not sure. Sorry for the long post but I tried to be complete with the history and details.
My pool information is in my signature and the issue I seem to have is what appears to be black algae growing in certain areas on the underneath side of our 14 month old CoverPools fabric cover (described by them as high-performance vinyl-resin formula with polyester mesh). The black stuff is embedded in the grids of the mesh. It only seems to be on the areas of the side edges where the fabric is not touching the surface of the water but is exposed to air. This is on the first 24" or so of the leading edge and on the first 6" to 12" of the sides. There is no sign of any algae on the top side of the cover or the vinyl liner (which I understand it cannot attach to) or any other component that I can see.
I have uploaded a few of pictures at the end of this post of what this looks like.
I will admit that some of this may have been under there for a while, as I don't normally peek under the cover much as it is usually fully retracted when I use the pool. But I seem to recall seeing some discoloration in the past when I left it not quite fully open and when I was in the deep end. I think I assumed it was just normal discoloration of the underside of a cover perhaps caused by exposure to chlorine.
The cover is always fully closed for about 23 hours per day.
I performed what I read is a test for black algae - holding a chlorine tablet on an affected area for 3 minutes to see if the area changed color. It did lighten up a bit. I tried to scrape some up with fingernail and see if it smudges to green but I cannot seem to get enough loose - the layer is so thin in the indented grids of the fabric.
The other issue that I have is water clarity degradation for the last 10 weeks - starting with a light oily type film on the surface of the water then slightly cloudy water and what seems to be a more slippery floor. This all started after I had my sand changed about 12 weeks ago. This was done by my pool service company. I do not know what sand was used, but they tell me it is what they use for all their residential and commercial accounts.
Within 10 days of this sand change my water started to get cloudy and film started forming on top. My free chlorine and pH went down. I added soda ash and another chlorine tablet and increased the feeder setting. I also increased my pump speed and turnover from 2 to 2.4 turns per 24 hours.
At the recommendation of the pool store I began to treat with BioGuard Pool Complete clarifier. The water cleared up in a couple of days and the "slippery" floor seemed to be resolved. But then about 7 days later the film returned and the water clarity declined. Another dose of Pool Complete temporarily clears things up again. After four cycles of this I continue to have the same pattern. Clear water after the Pool Complete, film and light cloudy water on day 6 and 7. And it struggles to maintain my steady state chlorine and pH levels.
There has been no change to the usage of the pool (just my wife and I for about 45 minutes per day); no new body oils, shampoo, lotion, etc. and no environmental change (it's an indoor pool). I am curious if the sand change had something to do with this. There is no sand in the pool and my Weir doors are operating normally. The pool company came out to inspect the filter and it looked fine to them.
My water for topping off the pool (usually only after a backwash) is from a well. The well water does have some metallic/rust particles at times, but I've never seen any of that in the pool - either when refilled from scratch from the well in 2021 or since. The total dissolved solids have always been about 800 to 900ppm.
My pool chemistry (as measured by both my Taylor K-1004 test kit and pool store) ever since the new liner and water refill and prior to the sand change been:
pH: 7.5 to 7.6
FC/TC: 3 to 5
CC: generally 0
TA: 100 to 120
CYA: 50
Phos: 500 (varies from 200 to 700)
This required minimal maintenance and just one 3" tablet every 10 days. Water was always crystal clear.
May latest readings as of 4/21 at the pool company lab are:
pH: 7.5
FC/TC: 2
CC: 0
TA: 105
CYA: 70
Phos: 200
And to maintain this chlorine I now need 2 pucks every 7 days at a much higher feeder setting. And I have backwashed 3 times since the water problems started.
My question are:
Based on the above, is it likely that I have black algae?
Does it seem likely that my water clarity issues are being caused by the black algae (even though it is in areas not in contact with the water and it may have been there a while)?
Is it possible that a sand change can somehow introduce water clarity issues or introduce/exacerbate black algae?
Given that whatever it is on the underside and in areas I cannot access, how do I clean and kill it? I cannot remove the cover on my own to clean it as it runs in a track on roller and would require professional help. I can reach the areas under the leading side but my initial attempt to scrub with a diluted formula of Clorox had only minimal success.
One thought I had was to temporarily raise my water level to above the returns - to just below the cover tracks so more of the impacted fabric is touching the water. Then maybe increase the chlorine for a while to help kill it. Is that possible?
Thank you all for your advice and guidance.
My pool information is in my signature and the issue I seem to have is what appears to be black algae growing in certain areas on the underneath side of our 14 month old CoverPools fabric cover (described by them as high-performance vinyl-resin formula with polyester mesh). The black stuff is embedded in the grids of the mesh. It only seems to be on the areas of the side edges where the fabric is not touching the surface of the water but is exposed to air. This is on the first 24" or so of the leading edge and on the first 6" to 12" of the sides. There is no sign of any algae on the top side of the cover or the vinyl liner (which I understand it cannot attach to) or any other component that I can see.
I have uploaded a few of pictures at the end of this post of what this looks like.
I will admit that some of this may have been under there for a while, as I don't normally peek under the cover much as it is usually fully retracted when I use the pool. But I seem to recall seeing some discoloration in the past when I left it not quite fully open and when I was in the deep end. I think I assumed it was just normal discoloration of the underside of a cover perhaps caused by exposure to chlorine.
The cover is always fully closed for about 23 hours per day.
I performed what I read is a test for black algae - holding a chlorine tablet on an affected area for 3 minutes to see if the area changed color. It did lighten up a bit. I tried to scrape some up with fingernail and see if it smudges to green but I cannot seem to get enough loose - the layer is so thin in the indented grids of the fabric.
The other issue that I have is water clarity degradation for the last 10 weeks - starting with a light oily type film on the surface of the water then slightly cloudy water and what seems to be a more slippery floor. This all started after I had my sand changed about 12 weeks ago. This was done by my pool service company. I do not know what sand was used, but they tell me it is what they use for all their residential and commercial accounts.
Within 10 days of this sand change my water started to get cloudy and film started forming on top. My free chlorine and pH went down. I added soda ash and another chlorine tablet and increased the feeder setting. I also increased my pump speed and turnover from 2 to 2.4 turns per 24 hours.
At the recommendation of the pool store I began to treat with BioGuard Pool Complete clarifier. The water cleared up in a couple of days and the "slippery" floor seemed to be resolved. But then about 7 days later the film returned and the water clarity declined. Another dose of Pool Complete temporarily clears things up again. After four cycles of this I continue to have the same pattern. Clear water after the Pool Complete, film and light cloudy water on day 6 and 7. And it struggles to maintain my steady state chlorine and pH levels.
There has been no change to the usage of the pool (just my wife and I for about 45 minutes per day); no new body oils, shampoo, lotion, etc. and no environmental change (it's an indoor pool). I am curious if the sand change had something to do with this. There is no sand in the pool and my Weir doors are operating normally. The pool company came out to inspect the filter and it looked fine to them.
My water for topping off the pool (usually only after a backwash) is from a well. The well water does have some metallic/rust particles at times, but I've never seen any of that in the pool - either when refilled from scratch from the well in 2021 or since. The total dissolved solids have always been about 800 to 900ppm.
My pool chemistry (as measured by both my Taylor K-1004 test kit and pool store) ever since the new liner and water refill and prior to the sand change been:
pH: 7.5 to 7.6
FC/TC: 3 to 5
CC: generally 0
TA: 100 to 120
CYA: 50
Phos: 500 (varies from 200 to 700)
This required minimal maintenance and just one 3" tablet every 10 days. Water was always crystal clear.
May latest readings as of 4/21 at the pool company lab are:
pH: 7.5
FC/TC: 2
CC: 0
TA: 105
CYA: 70
Phos: 200
And to maintain this chlorine I now need 2 pucks every 7 days at a much higher feeder setting. And I have backwashed 3 times since the water problems started.
My question are:
Based on the above, is it likely that I have black algae?
Does it seem likely that my water clarity issues are being caused by the black algae (even though it is in areas not in contact with the water and it may have been there a while)?
Is it possible that a sand change can somehow introduce water clarity issues or introduce/exacerbate black algae?
Given that whatever it is on the underside and in areas I cannot access, how do I clean and kill it? I cannot remove the cover on my own to clean it as it runs in a track on roller and would require professional help. I can reach the areas under the leading side but my initial attempt to scrub with a diluted formula of Clorox had only minimal success.
One thought I had was to temporarily raise my water level to above the returns - to just below the cover tracks so more of the impacted fabric is touching the water. Then maybe increase the chlorine for a while to help kill it. Is that possible?
Thank you all for your advice and guidance.
