stony_corals - I think it is indeed a T5 issue otherwise 90% of T5 users would not be complaining about it. "N-limitation" is not a factor, but rather a secondary means to color them up after the fact - or turn them brown
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To compare MH and T5's is apples and oranges...different bulbs, different radiation emitions. I myself still struggle with answering why the paling happens. Is it too much light or too little? As far as uniformity goes, I found T5's not to be uniform at all. Here is a grid with levels in my tank.
