Its official, with this system, i am able to give my fish fast 100% water changes of the highest quality without using a siphon.
As a final tweak, I fitted the pumps with elbows and low profile strainers to get them as close to the bottom as possible to siphon as much water out.
I then run clean water into the tank as the tank nearly empties and the fresh water cleans off the entire bottom of the tank and the debris are sucked away.
The tanks are cleaned better using this system than i ever could using a mere siphon and hose.
In about 5 minutes, a single tank is drained, cleaned, and refilled... and this operation can be comfortably done on 2-3 tanks at once.