I can't help but feel like I have been a victim of effective marketing! I have tried multiple "enzyme" based products and I just have not had positive results. we bought the black light to be able to clearly see the urine spots. Not only does the urine not go away, but the smell is still there. I have tried soaking the area and letting it dry, I have sprayed, I have had the carpet professionally cleaned, and I think the only way to fix our problem is just to replace the carpet. I wish that rather than wasting $30 here and there trying this brand and that only to have the same bad result, I would have just put that money towards the new carpet fund! Bottom line, don't waste your money if you have CAT urine stains of any kind or old DOG urine stains.. The stuff just doesn't work. Just get the carpet replaced and start over.