I determined they were strong enough for the RDWC system. I have no airflow control over the stones at the moment so it's 26 Liters/min via two 8" stones. A 1.2 ratio.
Water circulation flow is 380 Gal/hr. Or 15 swaps.
Pushing a nute level of 620PPM (@700)
In a week or so, I'll pop on the C02 @ 1000PPM+