Lots of folks on FaceBook have been talking about weed control with other than Roundup....straight vinegar, vinegar based mixes, salt, boiling water, etc.. I got SOME kill in grasses in my brick driveway using that mix of vinegar, epsom salts and Dawn, but little effect on purslane and spotted spurge. I read all the labels today at Lowe's of gallon jugs of acidic cleaners, hoping to find one based on phosphoric acid.....sulfuric acid would be acceptable. But none. So for $7 I bought a gallon of ZEP tub and tile cleaner containing glycolic acid, which is made from sugar cane and is in many creams and lotions to deep clean skin and reduce wrinkles. I'll use up the rest the vinegar based spray on the driveway, then try the ZEP on my carpeted driveway where nut sedge has gotten bad. I'll keep people posted on the results.....$7 for a gallon of a natural acid would be great...IF it works!