Newbie could use some pointers

[WuHT]

Its a 150 gallon, I don't really have a set water change schedule, but it seems about 10% biweekly, sometimes more, sometimes less.

I'm using the instant ocean brand (mainly due to cost) but i've being using this for a long time, and it just seemed like the problems have started recently.

Actually the T5s are HO (how does one tell if the bulbs are bad ?) I had the NO T5 strip lights before and the bulb simply wouldn't work (thats when i changed it).

Value wise, maybe just spending more on higher grade "reef" salt might be the better fix as opposed to going out to get test kits/dosing material, but I was just curious because i've been using IO for a long time. The whole point of the fowlr was supposed to be a low maintenance tank (free hitchhiker corals that I should try to save though)? I don't want to sound like I already had a plan set before I asked, but i'm trying to gather some opinions here.