From local pet shops usually for the common ones like nitrates/ammonia/pH/GH/KH/Alkalinity. The uncommon ones like phosphate, copper, calcium, CO2 and iron from special orders, ebay, or just very specialized pet shops.
The iron and CO2 liquid test kits aren't that useful though since they are essentially 90% inaccurate.
The iron and CO2 liquid test kits aren't that useful though since they are essentially 90% inaccurate.
