PO4 4,9 ppm? 😵
Well if i'm using this http://www.theaquatools.com/fertilization-calculator , its says adding 15 gr KH2PO4 to 1000 ml water and fertilizing 20 ml per day gives 0.7 ppm PO4 per day , thats 4.9 per week , thats very low in my opinion
But tank looks great !