Swimming pools blog

I am getting ready to open my pool for the season. Last year I had
continual problem with green algae forming on the pool floor and
walls. the thing that i couldn’t understand was, I had the chlorine
level quite high. Someone told me that the liquid would deal with
this better.???? does the alkalinity, calcium hardness etc all have
an affect on the formation of algae?
On a related note, when i backwash my hayward perflex filter after
bumping how much DE do i have to add? It’s so frustrating not
knowing how much is still in there without dismantling the whole
filter. Thanks for any guidance!
cbc