The Ultrameter II 6P must be switched to the resistivity parameter. First, you want to ensure that the pH cap is secure and will not allow contamination from the pH sensor well.
Hold the instrument down at a 30˚ angle allowing the sample to flow over the cell cup and down away from the user. Let the sample flow continuously into the conductivity cell. If sample is from a spout, bring unit as close to the spout as possible to avoid aeration and atmospheric contamination.
Source: Myron L FAQ