Redfield Ratio
Redfield Ratio
Now research on the Redfield Ratio mostly pertains to phytoplankton, but it does provide some good insight on the fact that photosynthetic organisms need Carbon, Nitrogen, and Phosphate. I am going to suggest that with your nitrate levels at near zero and your phosphates at .1ppm, your water is out of balance.
I have been enjoying five months of pale color and STN'ing SPS. I HAD a beautiful SPS tank last year and it slowly faded and then in February, I began losing colonies at a frightful rate. I went through and eliminated ALL other concerns regarding stability and chemistry and still, each week, the creep would start up on another colony.
Well, the other day, it dawned on me that I might be starving the tank. I have always been stingy on feeding and nutrients in the tank and running zeo, I was thinking that maybe I had over stripped the tank.
Well, I headed down to my LFS where the shop owner has a masters in something related to marine biology or icthyology and I began a discussion with him about adding potassium nitrate. He cautioned me about algae blooms if my Redfield Ratio is upset, but said to test for nitrate and let him know.
Well, turns out, zero nitrate and zero phosphate. I have since fed much more heavily to bring phosphate up, and added a teaspoon at a time, potassium nitrate to the tank to bring the nitrates up to 3ppm.
Remember, this is anecdotal, but over the last week of this approach, the necrosis has stopped and I have had an increase in coloration.
Bottom line...maybe your tank water is too clean...