FIL was an irrigation contractor and had a backhoe, so he dug our pool. 18x44 3 foot shallow end, 12 feet deep end, 40,000 gallons.
When first built in 91 we had salt system, reminded me of swimming in Salt Springs as was brackish as hell. Chain link fence we put around it lasted less than 2 years then rusted out.
Put a chlorinator on it and shock at least twice a month as we have a lot of kids in it and none seem to ever have to pee. (adults either)
I keep chlorinator full of tabs (damn things are 50 bucks a pound on amazon) put some algaecide and clarifier in once in a while. If it's clear and blue I don't worry with it.
Did the testing at a store a couple times and all it seemed like was they wanted to sell us a bunch of crap, crap that usually didn't work.
Do I know my ph level? nope, chlorine ppm? nope, any other tested thing? nope. Pool is blue, clear, and doesn't make anyone break out in whatever so I leave it be. hasn't changed anyone's hair color yet either.
What I did learn is to add one thing at a time, be it algaecide, clarifier whatever, wait at least 5-6 hours then add anything else it may need. I do keep a few bottles (8) of liquid chlorine on hand just in case.
And today my bride decided pool needed a bit of water added so she flipped valve on. I went for a swim after supper and water level was 1/2 inch from spilling over
We picked up a little vac attachment called a pool shark IIRC, it's about a foot in diameter. Hook it to skimmer and let it do it's thing, acts like a mini kreepy krawler