You're in sort of a tough spot: you don't want to change your water and disrupt the cycle, but you want to change water to lessen the algae's nutrients! You seem like a patient person who wants to do things the right way, even if it's the hard way. If I were you, I'd do the water changes and just know it'll be a little longer before the cycle is done. I'd bet that if some of that rock was really stinky, it was full of biological material that really kicked in your cycle, but also was full of algae food.
As a side note, you said you're circulating 1.5 times your water volume? The standard goal is 5 to 10 times your water volume per hour for the standard reef tank and much, much higher for SPS tanks. You may want to drop another powerhead in there and really blow things around some more!
I wish you the best!
Conni