I use a spreadsheet as well. Started it years ago as an Excel document. Recently bit the bullet & bought a new notebook since the old one was still running XP & the nagging end of support pop ups finally made me crumble. Don't have the latest version of MS Office, so decided to upload the document to Google sheets, since I have a Google+ account. Bit of a learning curve but functions much the same. A little nervous of having it on the 'cloud', but I back it up to a local drive from time to time.
It's grown into quite a complex thing with 12 different sheets covering everything from water changes, water tests, cost of hardware/livestock, electrical components & power consumption, LED specs, RODI gallons produced & filter changes.... the list goes on. Even have a sheet for calculating various conversions.
Here's a screenshot made some time ago.
Should anyone be interested, I can save a copy & link to a shared version to download or use as you wish although it may be confusing. There are no instructions & will probably be difficult to figure out everything I've done. I don't consider myself to be a computer geek, but I did get fairly proficient as an MS Office user in my previous line of work.