noob algae question

[madisonrose05]

good morning everbody

i have had this small 20 gallon tank running for a few months now
i decided i needed live rock, but was to cheap to purchase
25lbs of live rock fully cured so i bought 1 lb and was trying to seed it
with 20 lbs of uncured off the shelf plain white rock. i didnt know the
curing procedure before placing all my rock in the tank
my question is
what is this thick purple algea thats growing on my rock
at first i thought it was coraline algae but i have since changed my mind
it definitly thrives on light. if i leave the light off for a day
it will die off. if i leave the light on extended hours it seems to grow very fast. there are even little bubbles that form on top of this algae as its growin. pics arent the greatest but just trying to find out if this is good stuff or bad stuff i need to get rid of
sorry i dont know how to post a pic yet says file to big
thanks

 

[pinkie]

Is it like a reddish color? Is it all over the sand and rocks?

 

[melosu58]

if i leave the light off for a day
it will die off. if i leave the light on extended hours it seems to grow very fast.

It sounds like cyano and you seem to have found one of the answers. A week long lights out will help in the short term but you`ll need to find out what is feeding the cyano to cure the problem. Read this

http://www.aquariumadvice.com/article_view.php?faq=2&fldAuto=48