I have been cycling my tank for over 2 months with live rock. Ammonia count is 0 as is Nitrite. Lately I have quite a bit of algea growing in the tank... Brown, green and PURPLE. Should I be treating this with something or should I just scrape it off? I have not done any water changes since I started cycling but will now do a 30% change before introducing some hardy fish, is this correct? Is there anything else I should do before introducing fish?