What type of algae?

[chromakey]

Hi:

I am using RO/DI water. I did reuse the sand when I moved the tank last year. There was a lot of debris in it. This is my first saltwater tank. Do you think it is worth changing out the live sand? I was thinking going a bit shallower.

The livestock: 2 clowns, 1 flame angel, 1 sixline wrasse, 1 tailspot blenny, 1 tuxedo urchin and 2 cleaner shrimps.

Have you had issues chemical warfare with various corals?

Thanks again,