Prime for small refills, Safe for my big tanks' water changes.
Read the Fertilizing subforum stickies.
Research what causes your particular water cloudiness and fix whatever is wrong, if necessary.
Really. Those last two questions can't be meaningfully answered by anybody but you doing your own research.
But anyways.. I use Seachem Prime, by far my favorite.
Flourish Excel and Flourish
I don't use chemicals to make my water clear. Just mech and bio filtration. If your water paramter is right and stable, it should be fairly clear to crystal clear. For me, I just overfilter.
I'm not advising you use anything I typed unless you know what your problems are.
I also just use Prime for water changes and fertilizers. It depends on what type of tank and how much time/money you want to spend when it comes to fertilizers. There are a million types of filter media you can use to keep your water clean and clear, most folks here will recommend to use as few chemicals as possible.
Except for a good dechlorinator and conditioner (Prime seems to be the favorite), just adding chemicals is not the way to a successful tank. Planted aquaria are about balance: size of tank, lighting, filtration, substrate, plants, and animals all function as a system.
Chemicals? 
Re: Chemicals? 
Linear Mode
