New Water

[Reed Kadavy]

I drained my pool three weeks ago and began a new experience chlorinating with 10 pct liquid chlorine instead of the tabs I've used for a number of years. My PH is 7.4, AK at 90, CYA 30, and I have been keeping the chlorine level between 5 and 2. Today I noticed a faint shade of green on the north wall of the pool that gets no sun this time of year. Do I need a SLAM or would an algaecide be a better approach? Or do I just need to increase the chlorine level?

 

[Texas Splash]

It appears that algae has begun to creep into your pool in which case a TFP "SLAM" is in order (see link below). Make sure to lower the pH slightly to about 7.2 before increasing the FC to the SLAM level. For a CYA of 30, your FC SLAM level would be "12". Follow the guidance on that SLAM page and make sure to brush often. I suspect that even with chilly water, the FC simply got too low and/or perhaps the north end of your pool is more susceptible to algae growth based on available sunlight or circulation. Definitely NO algaecides. Just regular bleach or liquid shock (same thing). The Poolmath Calculator (Link also below) can help you with the proper dosage amounts. Good luck!

 

[cfherrman]

Don't forget regular brushing

 

[Reed Kadavy]

I drained my pool three weeks ago and began a new experience chlorinating with 10 pct liquid chlorine instead of the tabs I've used for a number of years. My PH is 7.4, AK at 90, CYA 30, and I have been keeping the chlorine level between 5 and 2. Today I noticed a faint shade of green on the north wall of the pool that gets no sun this time of year. Do I need a SLAM or would an algaecide be a better approach? Or do I just need to increase the chlorine level?

After the SLAM should I maintain a higher chlorine level through the winter?

 

[Texas Splash]

After the SLAM should I maintain a higher chlorine level through the winter?

Once you've passed the SLAM and all 3 criteria, it's important to consider the following:
1 - Never let the FC drop below the minimum. While the minimum FC for your current CYA is a 2, the ideal FC target is 4-6, so I would not let it drop below 4 for a while (after the SLAM) and see how things go. With chilly water, the FC should hold pretty well.
2- Make sure to brush that north side and/or any areas that may not receive good water circulation. In fact, it's easy to skip brushing in the winter simply because it's cold out, but make sure to bundle-up and do it periodically. Brushing breaks-up the biofilm that tries to grown on the pool's surface. I see you have a Navigator. I'm not sure how well that does in those areas, but supplementing with the brush should help.
3 - At some point, it may not be a bad idea to double-check the CYA one more time just to make sure you aren't lower than 30 and/or that you are indeed at the proper FC level.

Hope that helps.