Maintainance app, or pen and paper?

[FishyFishy!]

I made all of my logs in excel and printed sheets out. I keep them in a binder to fill out. Ones that are important to me right now is my vinegar dosing schedule and my carbon/GFO switchouts. But I also have test results, RO/DI filters, maintenance/water change sheets as well. Works good for me!