Detergent, Rinse Aid and Salt: What Each One Actually Does

Detergent: enzymes, not soap

Modern dishwasher detergent is an enzyme-plus-alkali system. Proteases attack protein, amylases attack starch, and the alkaline builders saponify fats. None of it foams, because foam kills spray pressure — never put hand dish soap in a dishwasher.

Enzymes need something to work on. That is why heavy pre-rinsing produces worse results: with no soil present, the detergent's active chemistry has nothing to bind to and residue redeposits on glassware.

Pods, powder and gel compared

Pods are the most consistent and generally best-performing option because they dose accurately and keep enzymes separated from bleach until dissolution. Their drawback is a fixed dose, which wastes product on light loads and under-doses very hard water.

Powder is the most flexible and cheapest per load, and lets you increase the dose for hard water. It absorbs moisture over time, so keep it sealed. Gel is the weakest of the three: it generally omits enzymes and bleach, and is best avoided if wash quality matters.

• Pods — best default; do not cut them in half, the compartments are sequenced.
• Powder — adjustable dose, good for hard water; store dry.
• Gel — convenient, weakest cleaning chemistry.
• Never — hand dish soap, laundry detergent, or bleach poured into the tub.

Rinse aid: the most under-used product in the kitchen

Rinse aid is a surfactant released during the final rinse. It lowers water surface tension so the rinse water sheets off surfaces rather than beading. Beads dry into mineral spots; sheets dry clear. It also speeds drying, which matters a lot on plastics and on condensation-dry machines.

In water above about 7 grains per gallon, running without rinse aid guarantees spotting no matter how good the detergent is. Keep the reservoir filled and turn the dosage setting up if you see spots, down if you see a slick or streaky film.

Dishwasher salt: only some machines

Many European-designed machines include a built-in ion-exchange water softener with a salt reservoir in the tub floor. Coarse dishwasher salt regenerates that resin so it can keep pulling calcium out of the incoming water. It is not table salt, and table salt's anti-caking agents will damage the unit.

If your machine has a large screw cap in the tub floor and the manual mentions a hardness setting, it has one — and if it has been empty for years, filling it will visibly improve results in hard water. Most US-market machines have no salt reservoir; for those, rinse aid plus a descaling schedule does the same job.

Diagnosing film on your dishes

White film that wipes or vinegar-soaks off is mineral scale: raise rinse aid, check hardness, descale. A slick or foamy film is too much detergent or wrong detergent: reduce the dose. Permanent cloudiness that vinegar does not touch is etching: too much detergent in soft water at high heat — cut the dose and use a lower-temperature cycle.