I have no problem with the heater, i have a few extra in my home. What i do with the water change is just add some distilled water that i put out for 24 hours and then pour it into the tank. I don't really work that hard for my water readings, except only for my 20 gallon which is doing fine. The scratches wont be a problem either because there wont be much activity near the tank or with the water changes (I think all of my tanks are acrylic and they're all in great condition [other than the pond] considering i had them for almost a year now).
Thank you for the advice though! Much appreciated.