Mass scrubbing advice

[sbcpool]

Was away on vacation for a few weeks, so the pool didn't get brushed or vacuumed for a while. I didn't think it would be a big deal. WRONG! My pool is covered in dots that do not brush off unless I spend about 5 minutes on each spot going back and forth with the brush using all my might to apply as much pressure as I can. There's no realistic way to do the whole pool this way. Unfortunately because of an ear condition I cannot dive to the deep end and do it manually, which would be faster but still take weeks.

The dots appear to be something stuck to the pool, almost like a tiny BB-sized berry or something. The only thing is there are no trees or bushes with berries anywhere near the pool at all. There aren't even any trees (berries or not) within 100 feet. I don't know what it is.

Any ideas for mass scrubbing would be appreciated.

 

[ajw22]

Probably algae.

Your PoolMath log has no recent complete tests. Show us your current water chemistry,

Do a Overnight Chlorine Loss Test and maybe raise your FC up to half SLAM level.

Try and let chlorine help as you brush the pool.

 

[sbcpool]

Weird. Until you pointed it out I wasn't aware that PoolMath wasn't tracking my logs anymore. Let me fiddle with the app and see what's going on. It might be that I started a new pool after the replaster in January.

EDIT - Fixed

 

[ajw22]

Note that your CYA is 50. If the dot disappears between 50 and 40 we round up and call it 50. You cannot eyeball values between the lines as the scale is logarithmic, not linear.

It looks like you are chlorinating with liquid chlorine.

You should be following the FC/CYA Chart which says for CYA 50 your minimum is 4 and your target FC is 6-8.

Your log shows at 3.8 you are below the minimum.

That all points to your spots being an algae problem.

The Free Chlorine and Cyanuric Acid Relationship

Managing your cyanuric acid and Free Chlorine levels is key to stabilizing your pool. Learn how these two items affect each other.

www.troublefreepool.com

SLAM - Shock Level and Maintain

We’ve all had to deal with a green pool. Clear algae from your pool with a SLAM! Read here to use shock level and maintain to clear your pool.

www.troublefreepool.com

 

[proavia]

Any chance fertilizer got into the pool?
Can you "carefully" scrape a few off and try smearing them on a paper towel? If so, what color are they when smeared on the paper towel?

Additionally, what were the CC, TA, CH test results and water temperature? They don't show in your PoolMath logs.

 

[dfwnoob]

Since it's likely you may very well be about to embark on a SLAM, you can save on your FAS-DPD test reagents by using 10ml of water and one heaping scoop of powder. Each drop of R-0871 would then equal 1/2 ppm FC. So 10 drops = 5 FC.

 

[flynwill]

My first thought is Black Algae

The pumice stone bricks sold in hardware stores for scrubbing toilet bowl rings can be effective, but will probably require diving. (I have memories of doing exactly that as a teenager.)