How much should my chlorine level drop a day? And strange yellow spots.

[TigerGalLE]

So I super chlorinated my pool right before going out of town using my SWG (18k gallon salt water fiberglass pool). Then I left It to run for 11 hrs a day at 40%. I was gone 5 days. When I got home yesterday my FC was still 13.5. I turned my chlorine generator to 0% and today it was 11.5 at the end of the day. Water temp is 80 and full sunshine today. Is this good? Normal? Expected?

I also have seen some yellow circles stuck to my stairs. It won’t vacuum off but brushes off easily. When I looked at it with my goggles it had a gritty texture. Is this algae? Or something else strange?

 

[Texas Splash]

So it appears you lost about 2 ppm of FC in 24 hours correct? If so, that's fine. It's when the FC demand exceeds 4 ppm without good cause (i.e. swim party) that we get concerned. Also, since you have a salt pool, ensuring your CYA is adequate (usually about 70 ppm) to protect the FC is important as well.

As for the yellow circles, I thought maybe pollen, but you said it was gritty. Do you have a sand filter? Your signature does not specify.

 

[TigerGalLE]

I do have a sand filter. We also have some exposed areas of dirt around the pool that the grass hasn’t grown all the way in. Sand does get in the pool at times from dirty feet but that vacuums right up.

I saw more spots today. They don’t vacuum off but I can brush them with my hand. It is really strange.

 

[YippeeSkippy]

Does it poof away or can you pick it up to feel it?

Maddie

 

[TigerGalLE]

Does it poof away or can you pick it up to feel it?

Maddie

I can pick it up but can’t seem to make it out of the water with it. Perfect little circles clustered together.

 

[TigerGalLE]

I took a picture today. My husband has been fertilizing the grass around the pool could it be that?

 

[Texas Splash]

My husband has been fertilizing the grass around the pool could it be that?

Sure looks like it could be. Try a seom crushed Vitamin C tablets on them or some Dry acid in a thin sock or nyon to see if that helps remove them.