Yes PPS Pro is the one I wanted to follow. So if I do so will I be fine with WEEKLY 20% WC?
I'm not sure where you're getting your water change "requirements" from. IE dosage is commonly done with high tech tanks. That typically calls for somewhat overdosing the ferts and performing a 50% weekly WC to reset the amounts in the water column. PPS Pro plan gets a little more accurate on the doses and doesn't require as much of a water change. 20% twice a week might be stretching it a bit, but it depends on your tank and your bio load and your fertilization method. I don't usually see people talk about 50% twice a week water changes unless they're keeping discus or other sensitive species.