Suction, at least in my case, is great as long as I have the water on as cold as I can get it, and full throttle. I have a 210 gal tank and do 20-30% water change twice a week. Total effort is about 25 minutes total, except every other Saturday when I do a major sweeping of the poo. That takes me about 40 minutes. Like I said before, being a newbie I can't imagine not having my python!