Yep, that is the problem we all face and those little cracks/crevices are exactly the places where we want flow to be (for several reasons). Getting flow where it needs to be and in the right amounts is one of the hardest things to accomplish (IMO). This is why wavemakers and powerheads like Vortechs have gained so much popularity. Truthfully, you will likely never get flow to be perfect, even in a smaller tank like this. A good practice (even if you have high-end powerheads) is to use a turkey baster or a small pump (your current PH will work just fine) to blow across your rocks every so often. I find it best to do this just before you start siphoning water during a water change so that you remove as much detritus as possible.
Congrats on your 1st edition. Looks like a Yuma.