I have two well established Sylvester Palms behind my pool that have been planted for 4 years. Within the past two weeks one of them have started to yellow quite quickly. I fertilize them both with 8-2-12 fertilizer with micronutrients so I'm not sure why one would yellow and yet the other one would be OK. Any help would be greatly appreciated as I am very worried about my palm! I was thinking possibly potassium or magnesium deficiency, but since I fertilize regularly I wasn't sure if this could be the case. Also a small amount of pool water got onto the grass between them recently, but it wasn't anywhere close to the roots so I didn't think that could effect it that much that quickly. The pool water overflows here on a regular basis during the summer and I have never had this issue. Here is a link to pictures of the trees:

Here is a link that might be useful: Palm Tree Pictures