how long does a DSB take to start working

I have had my 6" dsb in my sump now for about 2 months but
have yet to see any changes in how it looks, I expected to see bubbles start to appear in the sand but nothing appears to be happening. ​

 

Do you have a light over your sump? Most of what people assume is free Nitrogen being released by NNR isn't that at all. The glass takes the light down to cyanobacteria (kind of the way our atmosphere picks up light from the sun before it's even up in our area of the world). The cyanobacteria then uses this light and through the process of photosynthesis, creates Oxygen.

 

I have a cfl bulb equivalent to a 75 watt bulb above the refugium area with some live rock and a small amount of cheato. I used new dry sand when I set the DSB up, even my cheato isn't growing. No cyno at all the only thing I am getting is a thin film of green algae on the glass.