Cyanobacteria algea with 0 nitrates 0 phosphates

[maxwell50]

Hi I have 6 month old reef tank. I use api for testing and I get 0 nitrate and 0 phosphate but I got Cyanobacteria just on rocks. I started out with dry rock and seeded with bacteria throughout the cycle. I think I do feed heavy my 90 gallon tank. For flow I have icecap 3k at 60% and 1500gph pump on opposite side. For lights I got dsunny AKA Chinese black box. I have them mounted in my canopy which is low to water so their 1-2 inches above the water. From what I read Cyanobacteria is caused by high nitrates and phosphates , bad flow, bad lighting. I did mess with my light by trying different setting. I run skimmer and uv sterilizer and activated carbon in a bag. Since I don’t have any phosphates and nitrates how is Cyanobacteria feeding ?

 

[Neilth1]

it is most likely low because it is consuming the nitrate and keeping it low in your tank I have had good luck with cleaning my tank sand bed /sump and so on and increasing the flow where it seems to thrive good luck

 

[Hemmdog]

API is inaccurate so who knows what your nutrient levels are at. Cyano blooms at nero zero nutrients so it’s possible. Black boxes need to be at least 12 inches above the water.