I made my own stat sheet on Evernote with little check boxes for my parameters. Half of the people at Planted Tank don't test unless there is a problem. Some of them never test. I guess they never have problems or just know the right thing to do when a problem arises without having to test. I still haven't quite dialed in my EI dosing although I think I'm getting close. My Phosphate level is in line (no more green spot algae,) and I have a handle on Potassium. I reduced my Nitrate to fight algae but I think that was a mistake because my Anubias just sprouted a yellow wilted leaf. The algae was caused by too much light. Now I have to bump up the Nitrate. I don't think an app would have helped me with all of this. I pretty well remember the amounts of light, CO2 and nutrients that I have applied. Sounds fun. But maybe not necessary with just one tank.