One of which I am not... I found a bottle of EDTA (Ethylenedinitrilotetraacetic acid) in the shop and I wanted to know if I should buy it or not. I think it's 1 kg and it costs 35 euros (45 US$). On the bottle you can read: "Ethylenedinitrilotetraacetic acid, disodium salt dihydrate". Is it good for photographic use ? Is this a good price ?