Phosphate and nitrogen

[CoralClasher]

I have a 120 gallon reef not much for filters just the roller mat, bio pellet reactor and a good skimmer. My nitrogen seems to stay at three ppm but my phosphate will drop to 0.00 after one day of adding phosphate. My question is when should I be adding phosphate before lights are on or after they turn off? My rocks are stained green but no hairs. I do wonder if the green on the rocks is still alive and consuming the phosphate. How long can I leave phosphates at 0.00 before corals are affected? I've been adding phosphate every other day trying to stay at 0.02.

 

[SPR1968]

Hi Jon and welcome to R2R

A picture of your tank would be useful so we can see what’s what, but the green on the rocks doesn’t look to bad

The algae could be using the phosphate as a nutrient source which is why is showing as zero.

Also what test kit are you using as most do have a margin for error in the results.

 

[CoralClasher]

Using Hanna checker. I did turn off the lights for three days and phosphate went up to 0.7.

 

[Dburr1014]

Wrong thread

 

[CoralClasher]

Just want to see comparison pics.