I suppose I should clarify, the gel will not come in physical contact, just be in the same room. The way I worded it originally almost sounded like I was going to use it like fertilizer or something.
Since nobody else has touched this, I'll put in my 2c. , even though I don't have a direct answer to your question.
I'll use ona block when my plants start smelling, and I've had the same concern. My solution, without finding an answer, is to put a cardboard box, with holes in the top, on top of the ventilation outlet (with hole a hole cut in the bottom of course), and stick the ona in there. The box will make turbulence in the outlet airflow, making the air stay in the box long enough for the ona to work.
An added benefit is that I can hide all the electric cables inside the box, which in turn will make more turbulence inside the box.
That demands that the air vents on top, though. If you vent the air through the side of your grow area, I'd put the onas right inside the ventilation outlet. The smell from the plants will have to mix with the the ona molecules as they both get blown out the same hole. The ona molecules will also not come in contact with the plants, whether it's harmful or not.
From what I can find out there regarding people that use this it seems like many people do not put it in their grow room. I would have thought there would be more definitive answers based on how popular the product is. Odd.
I think you should check out Roseman's DIY Odor Control Bucket Thread There are many people in that thread that may be able to answer your question. I plan on using his idea in my grow tent if my carbon filter doesn't clean the air 100%.
