Adding new sand

[scsdukefan408]

So my sand levels got pretty low from my move and cleaning the junk off the sand during water changes. So my question is how can I add the sand? I had. Small diatom bloom from old bulbs, so is adding the sand all at once gonna cause a bigger problem then the diatoms I'm already getting rid of? Or should I just add a cup or so every few days or week?

Thanks guys