Got my kit, help interpret my first test!

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Re-tested CYA in full sunlight: Dot disappears right at 40. (Previously estimated 35-40 a few days ago, but I have been using the "40" CYA line for Shock FC amount)

Re-measured ACTUAL depth of pool, which averaged to 3.75ft (previously estimated it at 4.5ft - this has now been adjusted in Pool Math for 11,300 gallons instead of 13,500) Will perform truncated cones/radii estimation in a few minutes for further accurate test of volume.

FC = 14.5 (@10:30am)

Based on new Pool Math parameters, I added 25oz 8.25% bleach to reach Shock FC of 16.
 
Turns out I was actually pretty close with the LxW dimensions of the pool, it was the average depth I had wrong. Most calculators I am using with the new measurements are coming up with anywhere between 10,750 - 12,000 gallons. I guess at this point I will know based on what changes with my FC after I put in the alotted amounts. If FC skyrockets, I am probably on the lower end of this volume. If FC undershoots, I may be on the higher end?

I think for Pool Math's sake I will leave it at 11,300 and see what happens. Unless there are other suggestions...

FC = 16 @1:00pm

No new bleach added.
 
FC = 16 at 10:15PM
CC = 0

No new bleach added before bed.

OCLT results:
FC = 15 at 7:45AM
CC = 0

Water is clear.

I think this means I am done with the SLAM?? I have so much bleach that I will probably let it go through the rest of today with keeping it at/above FC = 16, to help me take care of the black algae spots a little quicker. I am still performing frequent brushing.

Then tonight I will likely stop running the pump 24/7 and go back to my 8-hour nightly schedule, but keep the FC between Target and Shock levels for the next week, before letting it drift back to Target levels where I will try to maintain it.

Thoughts?
 

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I would keep the FC at or near SLAM level until you have completely defeated the Black Algae. While the pool school article isn't mention running the pump 24/7, it definitely wouldn't hurt and can only help by filtering out more algae.

The only thing that will get rid of the algae is brushing. All algae and black algae in particular have a bio film that protects it from the chlorine, brushing removes the bio film and allows the FC to kill the algae. You are using a stainless steal brush, right? A regular brush will not help you defeat black algae.
 
Really starting to wonder if the black stain/spots on my steps and at bottom of pool is actually black algae. I tried taking a plastic knife out to the pool to scrape off a sample, but I couldnt get any to come off the pebbletec and onto the surface of the knife. I have no fingernails so can't scrape it the traditional testing way.

I have held FC at shocking levels (>16) for the past 4 days. CYA is 40. I have been scrubbing with a metal algae brush for the past 4 days, multiple times per day. Pump has ran 24/7 for 4 days.

This sounds really strange, but it actually seems to me like the area of black spots/stain on my bottom step is actually getting worse. it is almost as if I am spreading the black color around the areas. It's dark now so I can't take a current picture, but a picture taken last week is below. You can see the areas along the bottom of the step. Similar areas are on another step at other end of the pool, and randomly throughout the floor surface. Call me crazy, but it seems like its spreading to more and more areas, despite my SLAM. Also of note is that the ends of my steel bristles look really black, kind of like I went to the bbq grill and cleaned the top grate.

I have rubbed a few of the spots on a different step with a trichlor tablet and the color/stain was removed. I have gotten pretty close to the spots on the top step and I don't see anything that looks "fuzzy" or other signs of "Green" as I have seen described for black algae on these boards.

My latest water sample reading taken last week was:
CYA = 40
pH= 7.8
TA = 150
CH = 300

My CYA and CH significantly improved after doing a recent partial drain. The TA and pH are high, and likely even higher than this right now as I have been SLAMing for the past 3-4 days. As I know the results will be skewed if I test right now d/t currently in a SLAM, I am wondering if I should add a bit of muriatic acid now to lower the pH or just wait until I am done with the SLAM.

Any idea what may be going on? Im just not sure if this is actually black algae or possibly a metal or copper stain, d/t my long-time high CH (450 before drain) as well as likely elevated TA/pH, which I have read elsewhere may be a culprit.

My water is crystal clear so this is super frustrating! And, I am starting to go crazy not being able to tell what is black pebble and what is a discoloration/algae/stain!!!

IMG_1873.jpg
 
Sorry you couldn't get a sample... try NOT biting one nail so you can try again. Hahaha!

Metal stains would be affected by a vitamin C tablet placed on them. Organic stains/algae by the puck. Maybe you have both going on?? Try a vitamin c tab too.
 
I will try tomorrow AM in better light to get another sample. The PITA is that the biggest area is on the bottom step and the floor, which will require me to get in the pool. Pebble tec is no joke though, its near impossible to get in there for a sample as that dang algae obviously goes within the rock surface.
 

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