Hallo I'm going to try using recycled glass as grow medium what do you guy's think ??? I been using limestone as grow medium my PH was always off 7/8 the results wasn't so bad because I kept my reservoir PH at about 4.5 and it was a hell of a job to keep it steady and now I don't think it will give me any problem since glass won't change the PH I think or I am wrong