The only thing I would ever trust is a activated carbon or charcoal filter scrubber. Sorry doesn't really answer your question but it's the only thing I've seen that takes a grow room back to normal.
I've only seen them made, I'm sure if you search in the growing sections someone will have posted a DIY version. Usually consist of fishtank charcoal, fans, and ducting
I just searched google, but I'm not sure which one to get. I'd rather buy one then make one. How does it work? Would this one work http://www.globalindustrial.com/p/j...mpaignId=T9F&gclid=CKO80sqO7rQCFRRbnAodHiQALg ?