Cyano?

[mrbacony]

I have had cyano in this tank before, but this looks different. It is only on the sand bed. My last 3 nitrate and phosphate readings are as follows
12.7, 14.4 and 7.1 for nitrate while phosphate is 0.04, 0.09 and 0.11. These readings are from the last 3 weeks
I know the phosphate is a bit high. I need to change out the GFO, but this has been on the sand bed for at least 4 weeks.

 

[Reeflix]

diatoms? your tank looks pretty old though.

 

[mrbacony]

Yeah it is a little over 3 years old. It does look a lot like diatoms though

 

[Dan_P]

I have had cyano in this tank before, but this looks different. It is only on the sand bed. My last 3 nitrate and phosphate readings are as follows
12.7, 14.4 and 7.1 for nitrate while phosphate is 0.04, 0.09 and 0.11. These readings are from the last 3 weeks
I know the phosphate is a bit high. I need to change out the GFO, but this has been on the sand bed for at least 4 weeks.

Hard to say what it is, but not likely cyanobacteria. I am leaning towards dinoflagellates because of how dense the biofilm is.

 

[mrbacony]

That crossed my mind as well, but normally that occurs when the nitrate/phosphate gets out of whack. Mine has been very consistent along with other parameters.

 

[Dan_P]

That crossed my mind as well, but normally that occurs when the nitrate/phosphate gets out of whack. Mine has been very consistent along with other parameters.

I have a feeling that the link between nitrate/phosphate concentration is tenuous, being almost nonexistent in older tanks. For the 0-1 year old systems, the link might work 25% of the time. This is a long winded piece of advice not to use only nutrient concentration as a species prediction method.