I always use RO water. My test kit is rarley used. The first few months with my aquarium I was all gung ho about keeping track of the parameters, yet I kept on having fish die on me. My wifes cousin, who has had a saltwater aquarium for years kept on advising me to leave my tank alone. The less I mess with it, the better. I listened, and slowly I started having less fish loss. Now, I just do a 10%-15% water change every 3 or 4 months. I'm already due for another. I'll try changing bulbs, just don't like the fact of changing $60 bulbs every 6 months. But if I it works, then I won't have a problem with it. My system is a simple set-up. I have a canister filter and a protein skimmer. Every few days I'll add supplements (C-Balance Part A & B), once a week I'll add trace elements, and I have a No. 58 block. I just hope this is enough for a fish only tank, but I wonder if it will be ok for when I start adding softies?