We opened the pool in April. Got everything balanced very nicely. After brushing walls, would repeatedly see significant rapid algae growth every 3-4 days only around the wall light at the deep end, even when the water was still around 68F (VERY cold spring here in MD). Like 10 square feet of green/black algae growth on both sides and below the light. So, I went in the pool about a week ago (+78F) with a screwdriver to open the light up and sure enough, there was a lot of old nasty gross algae muck inside the circular bezel holding it in place and all over the rear of the bulb itself. Cleaned the entire structure with a tooth-brush. The skimmer returns and rope holders a clean. No other hiding places for algae found. When cleaning the light....Most of it went into the pool water. Most of it got skimmed out first, then what was left filtered as it's no longer int he pool. These are the last readings from the "pool store" and they are in close agreement with my TFT Test Kit readings from three days ago:
ph=7.7
CC= way less than 0.5, almost negligible
TA=75
CH=288
CYA=62
Copper/Iron/Nitrates=0
Phosphates: 815
Salt: 3110
Saturation Index = +0.3
Three days ago after TFT test kit measurement and thorough brush of the pool I Raised the FC up to about 9-10 with Cal-Hypo, set my IC-40 CL Gen unit to make CL 100% of the run time (which is 10 hr/day), added a little acid just to get the Ph down to 7.6. I also added 40 pounds of salt because my IC-40 says it needs to be at 3600 ppm salt concentration for optimal results.
After three days I have a small number of green algae by the light only....about 1 square foot. FC is around 7.5. Ph is around 7.8 (added some acid).
So, I'm trying to figure out: why did the algae reform in three days by the light? What am I missing?
I have not backwashed sand filter since I cleaned the algae scum from the light: could that be a reason?
Get it out of the pool system?
Pool water looks clear, maybe a little hazy but pretty darn good.
Thanks
Mark in SO. MD
ph=7.7
CC= way less than 0.5, almost negligible
TA=75
CH=288
CYA=62
Copper/Iron/Nitrates=0
Phosphates: 815
Salt: 3110
Saturation Index = +0.3
Three days ago after TFT test kit measurement and thorough brush of the pool I Raised the FC up to about 9-10 with Cal-Hypo, set my IC-40 CL Gen unit to make CL 100% of the run time (which is 10 hr/day), added a little acid just to get the Ph down to 7.6. I also added 40 pounds of salt because my IC-40 says it needs to be at 3600 ppm salt concentration for optimal results.
After three days I have a small number of green algae by the light only....about 1 square foot. FC is around 7.5. Ph is around 7.8 (added some acid).
So, I'm trying to figure out: why did the algae reform in three days by the light? What am I missing?
I have not backwashed sand filter since I cleaned the algae scum from the light: could that be a reason?
Get it out of the pool system?
Pool water looks clear, maybe a little hazy but pretty darn good.
Thanks
Mark in SO. MD