You test water parameters with a test kit. Look into the API master kit, it's one of the best.you can find them at petco and petsmart, and they're also on amazon. You start that vacuum by sucking on the open end, and pouring the water into a bucket
every time you strip that tank, you start your cycle over and open your fish up to even more disease then if you just left it alone.
welcome to AC by the way!!!