Water Changes

[Blind River Joe]

Hello:

Just looking to see what other people out there do for water changes. I have a 250 gallon tank and I change 40 gallons of water per week. I don't have a huge bio load. My sump is 70 gallons with a skimmer. I have 250 lbs of live rock. I have a Tunze wave maker and all soft corals. Currently all water parameters are in range. The reason I am posting this question is I have been told that I change my water too often and too much. I am considering changing 20 gallons every week instead of 40. Any thoughts would be appreciated.