I'm in no way knocking your LED's but those could be a reason why your SPS may look bad. By I am not a fan of lED I have seen them screw up people tanks, but hopefully your not one.
Any way I do not test for strontium, I add 5 TBS every Sunday unless I do a wterchange that weekend. Along with strontium I dose baking soda for alk, I top off with Mrs wages pickling lime in my top off water and magnesium. I have tried to spot feed in the past but its not success flip ever. I have 17 soon to be 18 fish in my 180 ranging from small to xlarge, they will grab the food before it has a chance to eat.
I have family that live in Albion pa which is 15 miles from the border of PA/OH maybe even trade frags of chalice. Please do not taking the lighting comment to heart it's just my view on LED's and what I have seen.