black algae all over my sand

[perenes]

Am sick of this algae all over the sand, I change the water and clean the sand but in the next day will come again, its on my rock to. any ideas

 

[Mavrk]

Is it black or a deep red? Sounds like Cyano to me. Do you have any pictures? Or is it more of a powder than a slime? How old are your bulbs? What are your parameters?

 

[perenes]

parameters are good but i think the light is the problem, am getting new light in friday

 

[perenes]

is some kind of dark purple angae, nasty