Haven't tried Con-Crete but I have seen good reviews on it. As Brad1224 stated, as a personal trainer you shouldn't be professionally suggesting any supplements to your clients. What you can do, however is explain what a supplement does and explain how it is generally taken. If you suggest a product to a client and they dehydrate themselves while taking it and end up in the hospital or dead you're looking at a hefty lawsuit that Personal Trainer Insurance will not cover, as this is not in your scope of practice as a personal trainer (I'm ISSA certified and am always very careful about discussions with members or clients about supplements) That being said, Creatine Monohydrate has the most scientific studies done on it BY FAR and has been proven effective multiple times. If you tell clients what it is, tell them to research it or show them where they can find research on it, and tell them that you "Cannot suggest taking this product as that is not my job or qualification, but here is information on the product so that you (client) can make an informed decision" - then you, your client, and your business are all safe(r).