My zoas Some of my SPS are a little faded, so 2 weeks ago after some reading I decided to start dosing sodium nitrate (food grade). I dosed 1ppm nitrate daily for 5 days but my nitrates stayed at 0.25ppm the whole time. I'm guessing due to the carbon dosing the nitrate I was dosing was getting consumed rapidly by the bacteria. I kept dosing nitrate at 1ppm for another week, and all of a sudden I noticed some burnt tips, and some of my SPS not looking happy. I immediately tested and my nitrate was now at 4ppm. What I think happened was that at some point, the trace amount of phosphate in my system got stripped and phosphate became limiting.
I have a very similar experience a couple times now. I just resumed NaNo3 dosing 5 weeks ago using Lab Grade Sodium nitrate from The Science Company, dosing 0.75 ppm every night and by morning the NO3 was undetectable using Salifert and Red Sea Pro kits. I didn't notice any difference in my SPS until the 2nd week when suddenly everything stopped growing and I had to stop 2-part dosing completely. 3rd week I'm keeping steady between 0.75-1 ppm NO3. 4th week I have burned tips on Montiporas (Acros look ok, but pale) and still no 2-part dosing so I stopped NaNo3 dosing. This whole time PO4 has been undetectable on Hanna ULR meter. I don't use any GFO or such.
The first time I got burned tips from this same dosing with the same product I had a similar experience where the corals stopped growing and I had to stop 2-part dosing, but I didn't catch it quick enough and had an alkalinity spike. I contributed the burned tips to the alk spike, but now I'm wondering if my burned tips are from the NaNo3 dosing stripping the undetectable PO4 to true zero?? Or maybe there's an impurity in the lab grade stuff that is causing the stress??
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