I found one post that said to use this method
Take a Sock Poor your recommended levels from the Calculator into the sock and then take some string, and tie it off from the opening so it can't poor out. Then take another string ( or same one if long enough ) tie it to your ladder or whatever and position it in a way where the flow from the pump is flowing right through the sock. Let your pump run until there is no longer anything left in the sock.
The manufacturer instructions say mix with water and add through skimmer but it takes forever that way and it doesn't seem like it would disolve very fast in the filter.
so what is the fastest method to getting it disolved and reading accurate.