I have the full gamma of API test kits. (Ph, nitrate, nitrite, ammonia, calcium, phos, and I bought either the kh
but Idr at the moment). I use a fluval hydrometer. I also have a hm digital TDS
meter. I have a 92 gallon corner that is about 7-8 years old with a 20 gallon, 2 chamber, sump with a filter sock and live rock as the only media in it. There are two 150w metal halides with 20,000k bulbs in it(which are lord knows how old) and two t5ho with 460nm blue actinics (Red Sea) that I installed two weeks ago.