I can't believe you guys are dogging on Ona Gel so much, lol. Carbon filters don't work 100% either yeah know, but yes they work better than Ona Gel by far.
He asked if Ona Gel is worth it, and I think it is very much worth it. If you are worried about someone smelling your Ona then you are probably growing illegally, just saying.
I'd rather smell a clean scent of my choice than what the carbon filter kicks out. Carbon gets rid of 99% of it and you can't really tell what it is you are smelling, but there is a still "a" smell.
And you guys worried about smell and getting caught, you shouldn't be half-assing your air cleaning needs. Smell should be your first priority before even lights, nutes, strain, etc are even considered. It falls under that whole "stealth" category, lol.