TAN is the combined measurement of both toxic and non-toxic forms of ammonia in water. Test kits usually report TAN, and the toxic fraction of it depends on pH and temperature, which is why the same TAN reading can be dangerous in one pond and relatively safe in another.
Total Ammonia Nitrogen (TAN)
Lokorio
Certified Aquaculture Expert & Founder, Memeilo Ponds
Moses Lokorio is a certified aquaculture expert with over 6 years of hands-on experience helping fish-pond builders create healthy, balanced pond ecosystems. At Memeilo.com, he writes detailed, data-driven guides to simplify pond construction, maintenance, and fish care for DIYers and professionals alike.