I would like information on a nice size carbon bottle for water changes can anyone help me?

[Chris Derrick]

I have one 240 gallon tank and love to do water changes for my Petrochromis and really want to run my city water through a carbon bottle but not one of the small RV types a larger one with say 3/4 inlet and 3/4 outlet if any of you have done this please let me know where to get the stuff without buying everything from whole house water center they want $$$$$$$ and want to lease or rent it.... Thanks in advance. Chris