i didnt get any calibration fluid with it (got it from ebay ) only payed £9 so i cant complain but it looks brand new, no marks at all. i dont think even if i had the fluid i'd know how to calibrate it anyway.
i found tho by taking a reading yesterday and leaving the bucket of water out over night then testing it again i got 2 very different readings. seemed the PH went up by 0.5 over night which is quite a huge jump for a standard bucket size. hmmm now to get some calibration fluid, i bet that will cost a lot too can it be used more than once? anything to save on money