Update.
pH raised to 7.8 yesterday evening, so I adjusted back to 7.2 again.
Tonight is going to be 72 hours since I filled the pool. Would it be the right time to add CYA and chlorine. How do I do it? I have 3 chlorine tablets (3"), or should I use the method described below?
"the sock method is to add about 1-2 pounds of granular CYA at a time, into a sock- yes tube sock or long dress sock - tie a knot at the top and set it in your skimmer, off to the side, so it doesn't block the flow of water. This allows you to continue to backwash/clean the filter as needed without losing the CYA that's slowly dissolving. Depending on the flow of water it should dissolve in a day or so."
And finally, I have a pretty old filter (see the pictures). It is time to clean it. What is the easiest way to clean filters like that. Before I would open the filter, take out the filter plates clean them, take out the earth clean inside. Do I need to do any of that or there is a much easier way?
Thanks.