Run it. Now. To see where you are.
If ever things are going squirrel-ey---test your alk.

...Then test it weekly, during your first half year. Bi-weekly thereafter. This is for fish-onlies AND for reefs both softie and stony. For all tanks. Alkalinity is THE most important test for a reef, once you pass your cycling hurdle. And for a fish-only, alk controls so very much regarding fish health, just consider it an absolute essential. If it's right, you've got a major part of fish-care...

Do you need GFO: how to use it...RE PHOSPHATE AND ALGAE PLAGUE
Granulated Ferrous Oxide is, in effect, rusty iron pellets made porous, specifically to sop up and hold phosphate out of your water.

Rock, sand, and tapwater all contribute phosphate to your tank, and algae loves it...especially hair and film algae. Some rock is worse than others in this regard---but it can be some of the prettier rock. And 'new' rock goes through a period when it starts slowly 'leaking' phospate...

A few things many people don't realize...
1. bacterial colonization (cycling) goes on for some time after your initial 'ammonia' reaction, in the sense that life goes on colonizing your rock all the way to the core of it. This is why old live rock is tougher than nails---and why just-cycled rock is very fragile. This process (depending on how holey and porous your rock is) can continue for many months. This is one reason why we say go slow at first. Your rock won't be finished colonizing...

...

Do NOT buy coral while your tank is still having problems like massive algae, excessive cyano (most tanks get a little now and again).

Do not buy corals until you have 1) proper lighting 2) test kits to be sure your water is ok. And supplements to KEEP your water ok. 3) dips and in the case of softies (and stonies you don't trust) an observation tank with proper lighting.

First, the lighting. If you do not have light it hurts your eyes to look toward, no sps (colored...