Pool size, gallons?

Once you get your approximation, you can double-check and fine-tune your volume number using Pool Math, testing and dosing. So say you calculate 10000 gallons. And you measure your pH and it's 8.0. Then say you want your pH to be 7.5. So you plug that into Pool Math and it tells you to add 14oz of 31% muriatic acid to achieve a pH of 7.5. So you add 14 oz, circulate the water for about an hour, then test again. If you get a pH of 7.5, then you'll know your water volume of 10K is pretty darn close. If not, then you can adjust your water volume number accordingly. Repeat this same process for FC. Do FC at night, to take the sun out of the equation. Repeat these pH and FC "verification" processes until you're confident that your testing, dosing and water volume are producing expected results, and you're good-to-go.

Since the water volume number is primarily needed to calculate dosing, then once you get repeatable results from testing your dosing, it's mission accomplished...

Now this is all presuming you have a quality test kit. If you're serious when you said you'd "like to try to keep up with the chemicals," then buying a quality pool water test kit is your first step. And needed for the process I described above. TFP recommends only two, either is great. The TF-100 is considered here to be the most cost-effective. I have the other one, but they both work the same. Order yours right away and stick around here and we'll teach you how to use it and become your own pool's expert! It'll pay for itself in short order, especially compared to how much money you can waste on pool stores and pool guys.


Be sure to order a Taylor SpeedStir at the same time. That might seem an unnecessary expense, but trust me, the first time you use it you'll thank me! We all have one, and makes testing soooo much easier and accurate.

Oops, sorry. In case you don't know: Pool Math is an app for your phone. It's a handy tool to have and use, and makes pool care a snap. It helps you test and dose your water, and records all the results. It's a must have, and works on both iPhone and Android. There's a free version, to get you started, and a paid upgrade version that gives you all the bells and whistles.

There's also a webpage version, which is a calculator of sorts, that you can play with to see how the math works for testing and dosing. While they bear the same name, they are only vaguely related. The phone app is way more capable. The webpage version inspired the app. Here (the same link Marty gave you):
Old PoolMath Webpage