When i had them, before i knew of the No Planaria, i used it straight, splashed everything left it for 30min, then top the tank with water and left it for a bit longer then drained it. The gravel i had in a bucket of vinegar and hot water (about 1/1)
Even when using vinegar i dechlorinate, which i would need to use anyway as i had to refill the tank once everything was rinsed