help me understand???

So I got these hammers three days ago from a reliable private seller. They looked great in his tank so I took them home. At home I dipped them in the TM iodine dip as per the directions (5 minutes). Rinsed in fresh salt twice. And since nothing came off I add them to a lower flow, lower light...

I have a small sump I’m setting up for a nano reef I’m setting up. I don’t know what media to place in it. I’m doing a protein skimmer. But what should I add for media. A large particle, to a medium, to a floss? Then skimmer? If you can link me stuff on BRS or MD please do so, or even amazon...

I need whatever tips tricks and knowledge people can give me. This is my 2nd try the first time ended miserably all my fault with many mistakes. Now im starting fresh in a new house trying to get a tank set up for a Mantis shrimp and maaaaaybe two clowns. If all goes well in this tanks first...

Can someone please explain alkalinity regarding reef parameters in simple layman terms? Is it some kind of buffering capacity of many things, or an actual separate ion like calcium and magnesium? Thanks for taking the time... :)