I'm thinking I might have an algae problem, but I wanted to run it by the folks here first. The whole situation has me a bit baffled. Here is a little backstory:
A couple of months ago, I drained and refilled some water to reduce my salt content and ended up with a CYA level below 30. Given the hot and sunny weather in my area, I wanted to bring CYA up to more like 60-70, so I put the pH at 7.6 and did an OCLT (no detectable FC loss), then raised CYA to 50. I repeated the pH and OCLT (no detectable FC loss), then raised CYA to 70.
(All FC tests were done with a TF-Pro Salt kit. In each case, I did a CC test; the result was always undetectable, < 0.5 ppm.)
Since then, weird things have been happening.
Last night, I turned off the SWG and added a gallon of liquid chlorine (10%) to the pool, raising FC to 16. An OCLT showed a 7 ppm loss, meaning my FC went from 16 to 9 in less than 12 hours.
At this point, I'm thinking I must have an algae problem, and that a SLAM is the best way to proceed from here.
In case anyone is wondering, here are the other test numbers from a few days ago, using a TF-Pro Salt kit:
pH: 7.8
TA: 80
CH: 450
CYA: 70
Salt: Measured 3200 with Taylor test, reported as 3300 on controller
Also, the water is very clear; I see no visible signs of algae, but I understand that clear water does not necessarily mean there is no algae in my pool.
A couple of months ago, I drained and refilled some water to reduce my salt content and ended up with a CYA level below 30. Given the hot and sunny weather in my area, I wanted to bring CYA up to more like 60-70, so I put the pH at 7.6 and did an OCLT (no detectable FC loss), then raised CYA to 50. I repeated the pH and OCLT (no detectable FC loss), then raised CYA to 70.
(All FC tests were done with a TF-Pro Salt kit. In each case, I did a CC test; the result was always undetectable, < 0.5 ppm.)
Since then, weird things have been happening.
- With my SWG set to 20%, FC held steady at 5 ppm for a few days. I wanted it to be slightly higher, around 7-8 ppm.
- I raised the SWG to 25%; FC dropped to 4 ppm the next day.
- I raised the SWG to 50%; FC dropped to 3 ppm the next day.
- I raised the SWG to 75%; FC dropped to 1 ppm the next day.
Last night, I turned off the SWG and added a gallon of liquid chlorine (10%) to the pool, raising FC to 16. An OCLT showed a 7 ppm loss, meaning my FC went from 16 to 9 in less than 12 hours.
At this point, I'm thinking I must have an algae problem, and that a SLAM is the best way to proceed from here.
In case anyone is wondering, here are the other test numbers from a few days ago, using a TF-Pro Salt kit:
pH: 7.8
TA: 80
CH: 450
CYA: 70
Salt: Measured 3200 with Taylor test, reported as 3300 on controller
Also, the water is very clear; I see no visible signs of algae, but I understand that clear water does not necessarily mean there is no algae in my pool.
