Diatoms,cyano?

[Robert59]

Not sure what but my sand is getting purple?

 

[cromag27]

Diatoms are brown, cyano and spirulina are red.

http://reef2reef.com/threads/cyanobacteria-questions-answers-and-solution.253823/

 

[Humblefish]

Do you have any critters in there to stir it up? Like nassarius snails.

 

[Diesel]

A quick check for it is take a sample of the mats from the tank with tank water in a cup add a bit of H2O2 and see if it has a reaction. No reaction= spirulina.

 

[Robert59]

Yes I have little critters nassarius in the tank

 

[Diesel]

Very few CUC's will go after cyano.
All they do is eat the detritus out of there but most of the cyano will stay in the tank.
Remember cyano is a kind of bacteria not a algae.

 

[Robert59]

Maybe be water flow ? Not sure new at this my first saltwater tank

 

[Diesel]

Maybe be water flow ? Not sure new at this my first saltwater tank

Water flow sure has something to do with this as you want a good flow through out your tank and if you can't have that use CUC's to battle the detritus in dead areas where you don't have flow.
If I say CUC's I mean a Clean Up Crew.
Use Dwarf Ceriths Eats Diatoms, Algae, Cyano and Detritus on your tanks substrate and on rocks. Very hardy under normal water conditions.
Not sure how big your tank is but use about 50 for every 10 gallons, you won't see them during the day as they will hide in the sand and under rocks but Oh Boy do they clean.
Contact John Malone at http://181.224.140.5/