equipment

Test strips vs liquid test kit

Which testing method should you rely on?

Short answer

Liquid kits for ammonia, nitrite and nitrate, where accuracy actually decides an action. Strips are acceptable for a quick KH and GH check and for a rough pH.

Side by side

Dimension	Test strips	Liquid reagent kit	Favours
Ammonia accuracy	Poor	Good	Liquid reagent kit
Nitrite accuracy	Moderate	Good	Liquid reagent kit
Nitrate accuracy	Poor	Moderate — needs vigorous shaking	Liquid reagent kit
GH and KH	Adequate	Good	Neither
Time per test	Seconds	Several minutes	Test strips
Cost per test	Higher	Lower	Liquid reagent kit
Shelf life once opened	Short; humidity degrades them	Longer, but reagents still expire	Liquid reagent kit

Which to choose

Test strips

Use strips for a fast routine check when nothing appears wrong.

Liquid reagent kit

Use a liquid kit whenever the result will change what you do — during cycling, and whenever something is wrong.

One caveat

Both expire. Write the opening date on the container; an old kit produces confidently wrong numbers.