Under testing of the new chemical dosage calculator

Just redo the chemical dosage calculator, need to run some test before sharing to people. Perhaps if you have some ideas (see from picture), please suggest it to me, thank you.

Initially another dosage calculator was shared by a friend, I found it completely too complicate to use, that's how this dosage calculator was created by me. The first version is very simple and created in year 2007, and no improvement since 2008. This new calculator is the 8th generation, still has some room to get improve. After a few test on it, will upload it for sharing.