Inglorious if you're smart you'll by an LED. LED's are pretty much the best lights at the best value. A 4 ft is like 500 bucks, but it has 5 years of light. If you ge t5s i believe the bulbs last like 6 months and the light alone is about 300 bucks + bulbs are crazy expensive also LED's have a lot more options unless you get a high end t5. Topping off is because your water constantly evaporates the sale doesn't evaporate with it, therefore it makes your salinity raise because theres more salt then water. You top off with fresh water to keep it balanced out. I have a mark on my sump so I know where my water level should always be.