Red /brown /green sheet algae

[romperstomper]

Thought that I had dinos as snails seem to die and have red /brown /green on the sand and rocks but its also on the glass and when I scrape it off it comes off in sheets which the tang and angels enjoy eating my no3 is very high currently 40-50, P04 0.25 all other stats are within NSW levels which I'm working on reducing tank is around 5 years old live rock 10 years plus any ideas what I have ? Edit not the best pics but before adding a diamond goby the sand was also red/brown the glass growth also looks very red under kessil blues .

 

[Doctorgori]

you sure they are eating the red stuff? or are they eating the green?

 

[Dan_P]

Thought that I had dinos as snails seem to die and have red /brown /green on the sand and rocks but its also on the glass and when I scrape it off it comes off in sheets which the tang and angels enjoy eating my no3 is very high currently 40-50, P04 0.25 all other stats are within NSW levels which I'm working on reducing tank is around 5 years old live rock 10 years plus any ideas what I have ?

Photo under white light might help

 

[romperstomper]

you sure they are eating the red stuff? or are they eating the green?

you may have a point .

 

[romperstomper]

Photo under white light might help

added