Good Morning to you all, I was in need of some tap safe for a water change and as I finish work at 7pm there was no lfs open, so off to tesco I went and noticed they sold this Bob Martin Tap Safe, I got it and have done a 25% W/C, I know I am going on a little bit and going round the world to ask my question BUT........ has any body used this before and is it any good? My water all seems to be ok but I am just a bit unsure as if its any good due to its cheap price. (£2.99 treats 250ltrs)