Measuring & Control — Measuring Jugs

Nutrients are dosed in millilitres per litre, which is exactly the range where a kitchen jug stops working. You cannot eyeball a booster at half a millilitre per litre, and with concentrates twice too much is not a small deviation but a different feed altogether.

Match the vessel to the amount

Jugs run from 50 ml to 3 litres, in clear polypropylene with a graduated scale and a handle. You read most accurately in a jug that stands full enough: 20 ml in a 3 litre jug is a mark just off the bottom, while in a 50 ml jug it is a readable level. That is why having several sizes helps more than one large jug for everything, and not because the large jug is any worse.

Syringes and pipettes for the small amounts

Below 20 ml a jug becomes awkward and you reach for a dosing syringe, available at 5, 10, 20 and 60 ml. It draws straight from the bottle, so nothing is poured over and nothing is left behind in an intermediate cup. For products you add drop by drop, such as pH down, there are pipettes at 3 and 10 ml: you correct in steps and measure in between, rather than overshooting in one go and having to come back.

The sample beaker is a method

The soil sample beaker is not a measuring jug but the way you test your substrate instead of your feed water: you mix a soil sample in it with distilled water and measure that mixture. The distilled water is not a detail, because tap water brings values of its own and you would be reading those as well. What you take the reading with is under pH Meters and EC Meters.

A fixed order prevents mistakes

Measure each product separately and add it to your water on its own rather than bringing two concentrates together in the same jug. Rinse in between, because a remnant of the last product counts towards the next one. And always measure in the same order: that way you notice yourself when you have skipped a step.

Frequently asked questions

Which size do I need?
Look at the smallest amount you measure regularly and choose for that, not for the largest. The big jug turns up on its own once you are mixing your watering.

Why a syringe when I have a jug?
Because a syringe draws from the bottle and goes straight into the water. That removes a pouring step, and every pouring step leaves something behind.

Can I use the same jug for everything?
You can, as long as you rinse. In particular you do not want pH down and a concentrated feed one after the other in an unrinsed vessel, because then you are reacting them before they were ever diluted.