SWG with normal chlorine level but have a few small green spots on skimmer, lights, and floor

[edlewis328]

Location: Northwest Missouit
Test Kit: Taylor 2500
Current Levels:
FC: 2.5
TC: 2.5
PH: 7.6
Alk: 100
CH: 110
CYA: 40

A few weeks ago started seeing green spots. SWG was only set at 45%. Chlorine level was pretty much 0-1. Vaccumed with robot, brushed and shocked. Raised SWG to 60% and seemed ok for a week. after about a week start seeing green moss around bottom edging of pool stairs. Chlorine tested at 4. Added in a few gallons of liquid chlorine, brushed, and vaccumed. All week has been ok as well as levels. Had quite a bit of rain Friday/Fri night. Go out this morning and light green areas again. Now in skimmer area and on stairs amd floor. Levels listed above. What is happening?!! did notice husband turned SWG back down to 45%. What does everyone run thier SWG at? Have VS pump we run on low 9 hours a day. Should we be running on high some of that time? Currently have robot vaccum getting what it can. Planned on brushing again and shocking. Raising SWG to 60%. Do I backwash before I shock? Any help/suggestions would be appreciated!

 

[mknauss]

Welcome to the forum!
With a SWCG, we recommend a minimum CYA of 60. Your low CYA and very low FC levels are allowing algae to take hold.
But as you have algae, do not raise it yet as you need to SLAM Process
Can you verify what test kit you have? Taylor does not make a 2500 model. They do make a K2005. If that is what you have, you need a FAS-DPD test kit to measure FC above 10 ppm. It is available at FAS/DPD Chlorine & CC's test
I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.

 

[edlewis328]

sorry I have the Taylor K-2005.