Hi, I've been racking my brain trying to figure why some of my SPS are fine, while some have turned oddly grayish. Growth is not what it was in my previous SPS tanks. This time however, I have a remote DSB with 3' mangroves plumbed to the display. My NO3 stays at 5ppm with heavy feeding and my PO4 drops about 0.05 per week. I need to manually add seachem phosphorus to keep it available. My question is, since my nutrients drop, probably due to the mangroves, couldn't I have a drop in elements like K and Fe which would contribute to my not so awsome SPS growth/color? According to my salifert potassium test. My level was 380ppm. I've been dosing 15ml /daily to boost it . Too early to tell. Just curious of your thoughts. This principle of elements consumption is used by the Rs color program based on Ca uptake. Wonder if the nutrient side could be similar