Either new test solutions are prepared in clean chambers and surviving eggs and larvae gently transferred into the new chambers, or the test organisms are retained in the test chambers whilst a proportion (at least two thirds) of the test water is changed daily.
Les substances de référence doivent se dégrader dans un laps de temps relativement court, sinon il est recommandé de recommencer l'essai en utilisant un autre échantillon d'eau de mer.