What are the best test kits available in the UK for NO3, NO2 and PO4? I am interested in testing water in a eutrophic freshwater lake as part of a water monitoring project, and thought you lot would be the guys to ask. Are the cheap 'dip strips' accurate enough? I assume individual kits would be best, but are there any makes to avoid? Are there any scientific papers on the subject? Any help much appreciated, thanks.