As other mentioned! every setup is different from one another. Although, it only takes me less than 10 minutes (10% on the 125G) and 5 minutes (20% on the 29G). I personally preferred not to do as much water changes on my tanks. For the last 2+ years, I change my water every 1-2 months. But for some reason, in the last 3 months, my red plating monti DEMANDS water change every 2 weeks. Around the 10 days mark, it start to bleach and color back right up after water change. I have yet figure why, hopefully I can figure it out soon so I can get back to being lazy !