I can't answer the questions about the tools you are interested in for this small of a pool. Perhaps someone else will.

But I will tell you that an outdoor pool needs to have some CYA. Without it you will lose too much chlorine to the sun and probably be having to either take the chlorine level too high to make it through a day without losing it all (which wouldn't be good for the liner) or you'll have to be adding chlorine 2 or 3 times per day.

A better option is to add some CYA to get to a level of about 40 or so. That will allow you to add chlorine only once per day, preferably in the evening. 3-5 minutes per day is not much time and would allow you to better enjoy the pool.

Can you tell us more about your situation? Do you have a drops-based test kit? Test strips are pretty worthless. Can you post a complete set of current water testing results? What are you using to shock and chlorinate with ---meaning ingredients.

Repost with info requested and someone can help you go from there. Welcome to the Pool Forum!