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Home & Garden

Tools for working out how much of something you need, and guides for the part a number does not cover — what order to do things in, and when it is safe to get back in the water.

Pool chemistry guides

The questions a dose alone does not answer

Every figure in these is checked against CDC guidance and EPA-registered product labelling, with the sources listed on each page. They exist because getting the number right is only half of using a pool chemical correctly.

All pool chemistry guides →

Pool water chemistry

Dose it right, in the right order

Pool chemistry is a sequence rather than a set of independent numbers, and doing it out of order is how people end up chasing a reading all season. Volume comes first, because every dose on every other tool scales off gallons and an estimate here scales straight through. Then pH, because chlorine sanitises poorly above about 7.8 — a pool that will not hold chlorine often has a pH problem rather than a chlorine problem. Only then chlorine or shock. Alkalinity sits underneath all of it, governing how far a dose of acid actually moves the pH.

Before you add anything: never mix pool chemicals, and when pre-dissolving, add the chemical to water rather than water to the chemical — the reverse can react violently. Add one product at a time with the pump running, and test before anyone swims. The re-entry guide covers what to test for.

Lawn, soil, fencing and decks

Spring yard projects, ordered before the season starts

A new lawn starts with the soil under it. Work out the topsoil first, because sod and seed both go on top of a settled layer, and a bed that is too thin is hard to fix once the grass is down. Then pick sod or seed for the same area. The fence and the deck are their own jobs, but they are usually planned in the same season, and both need post holes and concrete ordered alongside everything else.

Buying materials by volume or area

How much to order, including the part you waste

These answer the same shape of question — how much of something covers an area or fills a space — and they share the same trap. What you order is not what the job consumes: paint soaks into porous surfaces, gravel settles, concrete is lost to spillage and uneven ground, and offcuts are rarely reusable. Each tool builds in the customary allowance rather than leaving you to remember one, and each rounds up to whole units, because that is how the shop sells it.

Around the house and garden

Getting the specification right, not just the quantity

Two jobs where the usual mistake is the wrong unit rather than the wrong number. Fertiliser is sold by weight but applied by nutrient content, so two bags with different N-P-K ratios need very different amounts spread over the same lawn. Bulbs are still bought on a wattage habit left over from incandescents, when the figure that actually determines brightness is lumens — an LED drawing a tenth of the power can produce the same light.

Every home & garden calculator

The complete list, for when you already know the tool you want.