Instrument Preparation and Calibration

Biofouling is typically the controlling factor in determining the length of a maintenance interval for a continuous monitoring station. Using antifouling technologies will extend this interval, leading to fewer trips to the field and less time maintaining equipment. Antifouling is one of the easiest investments that saves money.

Reducing fouling also prolongs the life of the sensors and other submerged equipment and makes cleaning and maintaining the sondes faster and easier.

Tips:

• Use copper-alloy parts in YSI anti-fouling kits. Kits include copper optical sensor housings and larger wiper assemblies to wipe the entire surface of the probe; and copper sensor guards for further fouling protection.
• Use copper tape to wrap around plastic probe bodies.
• Use copper mesh screens on pH and conductivity/temperature probes.
• Use YSI C-Spray nanopolymer spray for biofouling protection of CT electrodes.
• You can also use a black anti-fouling paint on the plastic parts of your equipment. Pettit Paint's Trinidad SR (slime reduction) is an epoxy-based (hard) paint that will not rub off. You can also use Interlux Paint's Ultra-Kote. Mix paint well, as copper will settle to bottom. Two thin coats applied with a small brush are better than one thick coat.
• Also, cover sonde guard threads with masking tape and avoid getting copper paint on the metal parts of the instrument.
• Ablative paints can also be used. Water-based ablative paints are now available, although generally they are less effective.
• For plastic optical probe wipers, paint only the exterior and side surfaces. If you paint the bottom, the sensor may not detect the edges and know where to park.
• Paint ABS or PVC tubes at least once per year.

Download this slideshow for a demonstration on how to cleanly and effectively paint sensors with anti-fouling paint: How to Paint Water Quality Sondes and Sensors [PPSX in ZIP file, 829KB]

More Tips:

• Do not paint the sonde body. Instead, wrap it with plastic wrap and secure with rubber bands or tape. Make sure to make openings over the depth ports.

• Prevent small animals and detritus from entering the sonde guard: Use 0.25 inch plastic mesh (such as Aquatic Ecosystems N 1170) around guard. Wrap it around the outside of the guard 1.25 times and secure with a cable tie or rubber band. The mesh can also be painted with anti-fouling paint.
• You can also use copper mesh of the same size. It is more expensive but very effective and requires little maintenance.
• Remove all traces of fouling with mild dish soap and water. Soak instruments with hard growth in white vinegar to dissolve growth; soak up to six hours. Commercial products are also available in marine and boating supply stores.

Article: Long-term Monitoring Tests of YSI Copper-Alloy Anti-fouling Kits

Customer Forum: Before and after photos of water quality instruments deployed with anti-fouling kits.

A sound calibration procedure is critical to a successful monitoring program. It can save time and money by avoiding "bad" data and system downtime. Without a sound procedure, technicians will have leeway to interpret the steps, resulting in data of varying quality.

A good calibration procedure should be coupled with pre- and post-deployment checks to ensure the field data collected are valid.

Tips:

• Handle the sonde carefully during calibration to avoid damaging the sensors.
• Keep the sonde 3 feet (1 meter) away from electrical noise sources. pH and conductivity sensors can experience interference when operating in a noisy RF or high static electricity environment.
• In unattended studies, allow the sonde to record at least 2 hours of data before deployment and after retrieval to get the oxygen sensor performance data in the record for diagnostic purposes.

How to calibrate, maintain, and troubleshoot individual water quality sensors are covered in-depth in the YSI Calibration Tips Document. (Login/registration required to download.)

• Conductivity
• Temperature
• pH
• Dissolved Oxygen
• Optical Dissolved Oxygen
• Turbidity
• Chlorophyll

For Turbidity, see also the YSI 6136 Turbidity Sensor Calibration Video. (Follow link and click on Video tab).
Check out additional links in the Agency SOPs list.

Making the most of your monitoring budget comes down to maximizing the yield of good water quality data and minimizing system failures. Each step of the process is an opportunity for a mistake that can cost time and money. Programming the sonde for long-term deployment is one of the critical steps.

Carefully step through the series of checks to ensure your system is working properly prior to deployment.

Here are a few tips for programming, batteries, and O-rings.

• Set clock to the desired time - Standard, DST, GMT, etc.
• Note Free Bytes remaining. If you need more memory, delete files in Main Menu. Always check that your files have been successfully uploaded and you can open them before you delete them.
• Set specifics
  - Interval - Choose your sampling interval
  - Start Date - Current date
  - Start Time - Start the sonde immediately (pressing enter) so that logging can be verified.
  - Duration - Leave the setting at 365 days
  - Data Filename -8 alpha numeric characters only
  - Free Memory - Make sure there is enough to record the whole deployment or format the flash disk.
  - Parameters measured - Select your parameters. You will also want to collect battery voltage during the deployment as it can be an indicator for moisture in connectors or short circuit trouble. Battery voltage can be an excellent diagnostic tool!
• Use Duracell or Energizer brand batteries only; do not use RayoVac, generic, or NiCad batteries. If you do not use the recommended brands, then the sonde may overestimate battery days -- and possibly run out of power during your deployment.
• Check the polarity of battery case first with a voltmeter. One bad battery can cause loss of data within a few days.

More Suggestions for Batteries and Battery Cover:

• Dry thoroughly around battery chamber, unscrew, and remove O-ring. Wipe with KimWipe to remove debris. Even small particles will allow water into the chamber and short out the power supply.
• Insert new batteries. If refrigerated, first warm them to room temperature to avoid condensation.
• Inspect all O-rings on the battery cover or sonde body for contamination or wear.
• Clean O-ring with soap and water only. Be careful not to stretch O-rings. Nearby plastic can be cleaned with soap and water.
• Replace O-ring if removed and apply thin layer of grease to the rings. Too much may prevent a tight seal. (On YSI 6600 battery covers, the figure-8 O-ring can be installed dry.)
• On YSI 6600s, lightly grease the threads of the two mounting bolts. Press down hatch with equal pressure from 2 fingers. Make sure hatch wiper O-rings are not visible before tightening the screws. Do not over-tighten or you can deform the sidewall of the cover.
  On the 6920 and 600XLM sonde battery covers, wipe the cover surfaces with a KimWipe and inspect for scratches in the O-ring surfaces. Lightly grease the O-ring surfaces and install.

• Use only 3452 Dow Corning grease for O-rings. This is available from:
  - Polysi, 440-937-7777 or customerservice@polysi.com. Part # DC 3452; 57 gram (2 ounce) tube; $37.00.
  - YSI Inc., 937-767-7241 or 800-897-4151 or orders@ysi.com. Part # 601205; 2cc tube; $6.00.

As a final safeguard, the pre-deployment test allows you to check the complete system prior to a long-term deployment.

Wipers

• Install the deployment wipers.
• Confirm that both park at approximately 180 degrees opposite of the optics, or between 5 & 7:00 o'clock if the optics are at 12:00.
• Confirm that both wipers reverse direction during wipe sequence.

Optical Response

• Test each optical probe for response with its spare wiper.
• Each probe will show a full-scale reading when its beam is bounced off the wiper body.

System Test

• The night before a deployment, set up sonde to log data at same interval that will be used in the field
• Place in aerated bucket of water
• Check data the next morning before heading into the field to make sure sonde is logging properly and sensors are working

Tools for the Field

Accessing remote field sites can be a costly and time-consuming ordeal. Therefore it is important to have a set of tools and parts to address the unexpected.

Here is a list that we have developed over many years of field work that will allow you to tackle just about any issue related to a water quality monitoring station:

• 5-gallon bucket
• Deionized or tap water
• Squirt bottle for rinsing
• Allen keys for optical wipers
• Replacement wipers and pads
• Cleaning brush for conductivity cell
• Tool for sensor removal from sonde
• O-ring grease
• Kimwipes and cotton swabs
• Small voltmeter
• 2-inch wide soft paint brush for cleaning sensors
• Mild detergent for cleaning sensors, such as Clorox Green Works. Vinegar also works.
• Plastic bag for waste
• Rope for bucket, if you need to lower it into water for sample
• Personal flotation device

Also

• Flashlight
• Flathead and Phillips head screwdrivers
• Adjustable and needle-nosed pliers
• Batteries
• Zip ties
• Duct tape