algea

Question
QUESTION: i was wondering why it seems like no alge is growing in my tank im running live coral as a substrate i have three live rocks and three fish i have a fifteen gallon hex tank with a marineland filter system and a protein skimmer is there anything i can do to promote more growth?

ANSWER: Hi Anthony:  What are you promoting growth of???? the coral or the fish????

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QUESTION: ive seen tanks where the back walls are covered in different colored growths that appear to be an algea of some sort

Answer
Those tanks probably have a plastic mesh screen that is suction cupped to the back wall and in between the layers of screen are different types of algae... these you would have to buy specifically.  I have seen some of these kits for freshwater listed on ebay... you can look into that and if that is what you are talking about then let me know... dave