see if you guys can help me out here

[kingcoota]

my pool is a 20000 gunite inground
my plaster job needs too be redone
every place that the plaster cracks off
and it's down to the bare cement I notice
some black substance almost like algea. when i
brush it goes away or get alot lighter and i can
almost see some green algea getting dispearceing in
the water, but other than the spots without plaster, the pool
and the water are fine, any thoughts to get rid of the stuff

ph 7.3
ta 100
cl 3ppm
cya 40

[Watermom]

Take your chlorine level up to 15 and try and hold it there without letting it yo-yo up and down. Test your water 2 or better yet, 3 times per day, and each time, add enough chlorine to raise the cl back up to 15. Also continue brushing the pool and run your pump 24/7 while you are trying to clear this up.

By the way, what type of chlorine are you using? Your cya is currently at 40 which in my opinion is perfect and you don't need any more. Trichlor or dichlor both are stabilized and will cause your cya to continue to go higher which you don't want. Also, trichlor in particular is very acidic and will drop your pH. 7.3 is fine but on the low end of where you want it.

Can you also post a calcium hardness reading?

[kingcoota]

calcium is 320, but i also forgot to say that the tile which is just on the top three inches
around the pool also has some of the black substance algea just on the grout lines, but now everywhere just here and there.

After we swim today i'll load up on bleach and shock it for a day.

To watermom the chlorine i'm using is bleach but i have two 3 inch pucks left in the skimmer i dont plan to buy anymore though.

[Watermom]

Calcium level is OK. Fine to finish up your pucks. Won't add that much more cya. Good luck. Keep us posted how it is going.