Originally Posted by h20addict
Thats no good. Did another 15g change today, replaced my carbon and purgin again. Ordered new ati bulbs and new chemi pure elite so hopefully that helps
Those are diatoms. They will go away once all the Silicates are used up. It could be silicates in your sand or rock. Purigen won't make them go away. Water changes and time is all that will help. Cut your lighting photo period down a bit and use some Api PhosZorb or Seachem PhosGuard and keep up with water changes and it will be gone once all the silicates are used up. Diatoms are normal. And remember once you add something new to the tank, they will come back for a while and leave again.