406303A Black Algaetrine Swimming Pool Algaecide & Deposit Control, 32 fl oz, White

Will this work on a pebble - tech pool surface?

we drained our pool due to black algae. Can we simply scrub this on the walls? It has been empty for 3 weeks and we want to treat it and refill.

It just says to apply, does that mean while the skimmer/filter is running? Or should it be turned off when I apply?

Can you use this in vinyl lined in ground pools?