It is normal for newly set up tanks to go through algae blooms. The key to keeping the blooms temporary and not a constant problem is by reducing the algae's food. Using ro/di water, phosphate adsorbing media (phosban, rowaphos), aggressive skimming, replace PC bulbs before they shift into a red spectrum, use carbon (first soaked in ro/di water), and a refugium with macro algae will keep the algae starved
You can also get a few sand cleaners. Cerith snails and fighting conchs are two that I can think of. Also, remove/siphon as much as the algae out as possible. This will help export nutrients. It is all about exporting/reducing po4 and nitrAtes. Keep those low/zero and your tank will sparkle.
As far as adding sand, you can remove/siphon sand and then replace it with fresh using a cup. I fill the cup up with sand, place it next to the sand bed, then pour out the sand. I have added/replaced sand many times with no ill effects to the inhabitants. The water may be cloudy for a day but it will settle~