I have had my 12 gallon tank up and running with LR and LS for a week and plan to do a 10% water change tomorrow. Is that how often and how much I should change the water, once a week, 10%? Yesterday, I found some greenish mold around the tank walls, especially right below the light, behind the heater, and filter. accompanying the mold beneath the light are about 50 little (as in tiny, like 3mm in legnth) shrimp like things. What are all of these things, and what should I do to get rid of the mold? should I get rid of the mold?