I've tried re-arraigning my stones a few times to no success. It does effect the efficiency of heating -- but not the heat difference.

I've been thinking a bit of the fireplace fan and worry that it is going to be oddly placed and directed (might not accomplish it's goal), slightly dangerous since I'd have to take off the rock guard or might not even get hot enough to really get spinning

I've been researching more and thinking of getting something like this:

https://www.amazon.com/AC-Infinity-Cooling-Ventilation-Projects/dp/B009OWRMZ6/ref=sr_1_5?keywords=high+temperature+electric+fan&qid=1571153354&sr=8-5

Maybe even something that is a little slower spinning but dead silent. It would be SUPER easy to wire a few of these into the sauna to get the air moving around a bit more. I feel like computer fans might do a good job since computer temps regularly get in the hundreds and I can locate the power supply outside of my sauna. Something like this:

https://www.amazon.com/Noctua-NF-A14-ULN-3-Pin-Premium/dp/B00AA89BN4

I'll keep you updated.

DMA