Many people ask "What test kit should I use to test my tank water ?" or "My test kit says my nitrate is high ?", so before posting a question on test kits and hobby test kit results, please read the quoted text below from ceg4048's excellent article on "The Estimative Index (EI) Dosing with Dry Salts". "The Estimative Index (EI) Dosing with Dry Salts". https://www.ukaps.org/index.php?page=dosing-with-dry-salts What about Test Kits? I can think of three things I really dislike about keeping aquariums. The first is cleaning/removing algae, the second is water changes and the third has got to be testing. Normally, when a beginner walks into pet shop to buy his/her first tank, one of the first things the attendant will push is a test kit. Test kits are often included in a package deal. We therefore grow to associate teats kits as a normal part of aquarium husbandry so many are shocked when I advise to bin the kits. I’ll explain here my reasons for rejecting testing: 1. Hobby grade test kits, for our purposes are inaccurate. That would not be so bad in and of itself but they are also inconsistently inaccurate. This means that one day they can be merely marginally wrong and the next day the same kit can be grossly inaccurate. A simple change in humidity can throw off a kit’s response. 2. Test kits are expensive. The more accurate the kit the more expensive. Hach produces some of the more reputable test kits but they may be ten times as expensive as the basic kit. 3. The test kit, even the more accurate ones may not tell you anything that you don’t already know if you are following the dosing scheme. If you dose 7ppm nitrate this morning and your tank uses a maximum of 3ppm, then by the end of the day you know that you have at least 4ppm remaining. In the EI dosing philosophy you only care about having at least some target value in the tank. The objective is to avoid falling below the uptake rate limit. If you have more than this limit then great, but because you know how much you dosed you then know absolutely that you have at least that much. 4. The type of algae that develops in our tanks normally occur for specific reasons and due to specific nutrient deficiencies. The appearance of a certain type of algae therefore tells you what you what nutrient requires more dosing. EI therefore does not require testing because a known amount of nutrients are added to the tank thereby eliminating any ambiguity. Of course if you enjoy testing then by all means test, but just be aware of the pitfalls.