9.2 Levelogger Maintenance

Levelogger maintenance consists of cleaning the outside stainless steel casing, the circulation holes and the optical infrared eyes. The required frequency of cleaning is dependent on several aspects of the monitored water quality. In freshwater with good to excellent water quality, the Levelogger cleaning requirements will be very minimal; amounting to a seasonal or even annual maintenance inspection. In most cases cleaning can be accomplished by rinsing the Levelogger and using mild, non-residual, non-abrasive household cleaners using a very soft-plastic, bristled, pipe-cleaner type brush. Do not insert any object through the circulation holes at the sensor end of the Levelogger. In some cases simple cleaners are insufficient to properly clean the Levelogger. Several commonly occurring water conditions require specific maintenance methods, these include hard water, high suspended solids loading, biological or chemical fouling and salt or brackish water conditions.

Hard water monitoring can result in the precipitation of calcium and magnesium deposits on the pressure transducer as well as other components of the Levelogger. These deposits can be safely dissolved using a diluted solution (typically 10% strength) of acetic or phosphoric acid. Commercially available products for dissolving hard water scaling are also available and can be used if designed for household use. Some industrial strength hard water scaling removers are much higher strength and are not recommended for cleaning the Levelogger.

High suspended solids load may block the circulation ports or clog the internal pressure cell of the Levelogger. The potential clogging effect of solids deposition can be minimized by placing the Levelogger in zones of flow. To remove solids build up, rinse the Levelogger under a low flow of tap water until particles have been washed away.

Bacteriological or chemical fouling can be an important consideration in many ground and surface water monitoring projects. Sessile bacteria will often utilize installed instrumentation as an attachment substrate. Chemical deposit can be the result of electrical charge differential between the instrumentation of the monitored liquid or the result of biological or algal activity. Both forms of fouling can result in difficult to remove deposits on the Levelogger transducer, the conductivity wires and the Levelogger casing. To remove fouling use a diluted ( 10%) solution of sulfuric acid. Persistent material may require soaking for several hours.

The LTC Levelogger can be used for temporary monitoring in salt or brackish water. Continuous use of the LTC Levelogger in salt or brackish water is not recommended, as the salt or other pollutants may damage the Levelogger’s casing or its pressure sensor. To minimize this effect, regularly lift the Levelogger from the liquid; within seconds a thin protective layer will be formed by oxidation. To ensure accurate measurement, the conductivity sensor should be in close proximity to any zone of active flow in the groundwater monitoring well or near the screened ports of a stilling well. When completed salt or brackish water monitoring, ensure the Levelogger is thoroughly rinsed with tap or deionized water to prevent salt deposits forming on any Levelogger components as the water evaporates. Monitoring with the LTC Levelogger in polluted, salty, brackish or highly conductive environments will result in an increased conductivity sensor calibration requirement. See Sections 5.8-5.9 for more information on how best to determine whether the conductivity sensor requires recalibration. The second generation LTC has a ceramic body which is highly resistant to corrosion in salt water environments and can monitor in salt or brackish water without any corrosion concerns.

When being stored for extended periods, it is recommended that the Levelogger be placed in the protective foam shipping sleeve in a dry location where the temperature will not exceed the operating temperatures of -20° -80°C. It is also recommended that the logger be programmed to log at a 24 hour (1 reading/day) frequency. This logging rate will not cause appreciable battery drain, yet will exercise the transducer and electronics and actually prevent battery discharge. Ensure the installation cap or direct read cable optical connector are connected to the logger during storage.