Originally Posted by rsskylight04
For cycling you'll need to read ammonia, nitrite, and nitrAte.
If you're the curious type, eager to understand what is happening in the tank as it cycles, you will want to monitor pH, ammonia, nitrite, and nitrate.
For example, if you are doing a fishless
cycle, you will want to know whether the good bacteria are removing the ammonia you add to the tank. On the other hand, if you are doing a fish-in
cycle, you would be wise to keep track of the conditions to which the fish are exposed (in case symptoms of stress emerge).
I found the API Master Test Kit to be worthy investment and an indispensable tool for first-time cycling a tank. It includes all the supplies you need for these tests, except a device for extracting water from the tank. For that, I just use a clean bulb-style medicine dropper (i.e. one that has NEVER been used to administer medicine). The 5ml size is probably available at your local pharmacy. And 5ml is the ideal size since each of the API tests requires a 5ml sample.
For me, knowing the conditions provides peace-of-mind.