Start with your source water. Understand GH, KH and pH, grow a working filter and use the calculators with their assumptions in mind.
Water Chemistry
For almost everyone on mains water the answer is yes, every single water change. Here is what a dechlorinator actually does, why chloramine has made the old trick of letting water stand unreliable, and the one thing a conditioner will never do, which trips up a lot of hard-water keepers.
Water Chemistry
Driftwood is sold as a natural way to soften and acidify a tank, and on soft water it can nudge pH down. On hard, alkaline tap like mine it mostly just tints the water brown. Here is what tannins actually do, why carbonate hardness wins the argument, and when a piece of wood is worth adding anyway.
Water Chemistry
Rift Lake cichlid buffers and salts are sold as essential kit, but if your tap water is already hard and alkaline you probably do not need them. Here is what Tanganyika and Malawi fish actually want from their water, what my 22 dGH tap already gives them, when a buffer earns its place, and a homemade recipe for the people who genuinely do.
Water Chemistry
A high, stable pH is not the disaster the internet makes it out to be. Here is what a high pH actually does in a hard-water tank, why chasing it lower usually backfires, the one real risk worth respecting, and which fish genuinely thrive on liquid-rock tap instead of merely surviving it.
Water Chemistry
Reverse osmosis water is treated as a rite of passage in the hobby, but most fishkeepers do not need it. Here is how I decide whether RO is worth the money, the waste and the faff, and why my very hard tap water means I almost never reach for it.
Water Chemistry
Neocaridina cherry shrimp want a GH of about 6 to 12 dGH, and Caridina crystal shrimp far softer at 4 to 6. Why GH matters so much for moulting, and how to hit the right number for your shrimp.
Water Chemistry
A rough guide of 1 to 1.5 watts per litre suits most tropical tanks in a normal heated room. How to size an aquarium heater, when to go higher, and why two smaller heaters often beat one big one.
Water Chemistry
A stable pH anywhere between 6.5 and 8 suits almost every community fish. Why stability matters far more than the exact number, and why chasing a 'perfect' pH does more harm than good.
Water Chemistry
A plain-English guide to GH and KH for aquariums: what each number measures, how to test it, dGH and ppm conversions, and how to raise or lower hardness safely without chasing pH.
Water Chemistry
What the nitrogen cycle actually is, in plain terms: where ammonia comes from, the invisible bacteria that turn it into nitrite and then nitrate, why hard alkaline water makes ammonia more dangerous, and how you keep the whole thing ticking over.
Water Chemistry
The best hard water fish for a hard, alkaline aquarium: which species thrive on hard tap water, why you should not fight it, and how GH and KH really work.
Water Chemistry
What each aquarium water parameter means, what a healthy reading looks like, and what to do when it is off. Ammonia and nitrite at zero, nitrate low, and why stability beats chasing a perfect pH.