Synirr
"No one is a failure unless you try"
That's the system I've got, though my water changes are more in the range of 40% except for my betta juvies and fry, who get as much water changed as I can take out without leaving them high and dryThe systems with a water heater with tap water kept under pressure, heated, and used only as tap water is generally safe to use, as long as the water heater is properly maintained. I have this sort of system, and have been using heated water for years, without a problem. I do large water changes, 50 to 80%, on tanks that are 80F to 84F. Using cold tap water which is 50F or less with water changes of that amount would be a bad idea.
/www.practicalfishkeeping.co.uk/pfk/..._calculator.php