I just registered to take a look. While I may or may not use the app, my method for tracking is to use a spiral notebook to note all things pool related. One way that improve upon my notebook, as it relates to the Notes section, would be to incorporate Pool Maintenance tasks and allowing for classifications by using several levels of dropdowns. For example, dropdowns could inlcude:
Cartridge Filter Cleaning
Dirty Pressure _____
Clean Pressure _____
Notes
Sand Filter Backwash
Dirty Pressure _____
Clean Pressure _____
Notes
Sand Filter Deep Clean
Dirty Pressure _____
Clean Pressure _____
Notes
SWCG Cell Cleaning
Notes
Then there could be a lookup feature by type of maintenance task. So you could quickly see what your history of filter cleanings has been, along with the pressures and related notes.
You could also have an option for Notes/Maintenance Tasks that is "Other" which could then be given a name by the user for their own category which could also be searched upon.
I could see myself creating a permanent Maintenance Notes (which could be a dropdown item) note. This is where I would put information like the ratio of MA to water the I use to clean my SWCG, the process for cleaning my autocover, the socket sizes
for opening my filter, etc.
So basically, a more detailed tracking for maintenance and general notes/data, similar to what you have for the chemical side.