FIELD PROCEDURE:

EQUIPMENT NEEDED:

· “Maintenance & Calibration” binder

· YSI-85 multimeters

· YSI 5906 Membrane Cap Kit containing:

· new black plastic DO membranes

· small nylon scrub brush

· quarter-sized sanding disk

· oxygen probe electrolyte solution

· distilled water

· foaming bathroom cleaner

· [bucket]

· [commercial ammonia]

· [bleach]

· [conductivity calibration solution]

The YSI-85 multimeter is a hand-held field meter that measures oxygen, conductivity, salinity, and temperature. As of summer 2002, Streamkeepers does not monitor salinity except in some cases at grab-sample sites to test for tidal influence.

MAINTENANCE & CALIBRATION NOTEBOOK:

Record all calibration and maintenance activity in the “Streamkeepers Maintenance & Calibration” binder kept in the Streamkeepers office. See the binder for details.

CALIBRATION OF THE YSI-85:

Calibration requirements of the YSI-85 are as follows:

Ÿ Temperature: No calibration required.

Ÿ Salinity: No calibration required.

Ÿ Oxygen: Calibration is performed by the monitoring team on the day of monitoring. (See “Water Chemistry” protocol.)

Ÿ Conductivity: “System calibration is rarely required because of the factory calibration of the YSI Model 85. However, from time to time it is wise to check the system calibration and make adjustments when necessary” (YSI Model 85 Operations Manual, November 1998). In practice, Streamkeepers will not recalibrate for conductivity unless:

Ÿ the cell constant is not 5.0/cm ± 4% (per the Operations Manual); or

Ÿ the meter does not read between 975-1025 when inserted in a 1000 mS standard solution (±2%, per the Operations Manual); or

Ÿ monitoring teams note erratic readings, routine maintenance (below) does not resolve the problem, and the meters from two field kits do not agree within 4% when tested together.

If calibration is to be performed, procedure will follow the product Operations Manual referenced above, unless a revised manual supersedes it.

MAINTENANCE OF THE YSI-85:

Just before the quarterly monitoring period begins:

1) Clean the DO probe:

a) Unscrew the sensor guard at the end of the probe.

b) Unscrew and discard the old DO membrane cap.

c) Squirt the probe with distilled water.

d) Gently wet-sand the silver (Ag) anode sides and gold (Au) cathode top, preferably with two different marked sanding disks (provided with the Membrane Cap Kit), to avoid intermingling of the metals. Stop when darkening deposits have been wiped off—don’t overdo it! Rinse with distilled water and pat dry.

e) If the probe is still stubbornly dirty and unshiny, soak it in commercial ammonia (3% ammonium hydroxide – PAR ammonia is fine) overnight with the meter off, the membrane removed, and the membrane solution thoroughly rinsed off. The next day, rinse under running water for 5+ minutes and repeat the sanding instructions.

f) Install a new DO membrane cap:

· If you need electrolyte solution, prepare a bottle of it according to the instructions on the bottle in the Membrane Cap Kit.

· Holding the new cap upside-down, put in 15 drops of the solution.

· With the cap still upside-down, screw the cap onto the probe until it is snug—but don’t overtighten. Some membrane solution will spill out, indicating that the membrane cap is indeed filled.

· Examine the membrane; it should not be loose, wrinkled, damaged, or dirty, and there should be no bubbles under it. If there are problems, try rinsing, refilling, and reattaching the membrane, or discard it and try a new one.

g) Screw the sensor guard back in.

2) Clean the conductivity cell as follows:

a) Squirt a foaming bathroom cleaner (like Dow scrubbing bubbles) into the conductivity vents. Let sit for about 30 seconds.

b) Use the small nylon brush supplied with the unit to dislodge any contaminants from inside the electrode chamber.

3) Rinse the probe thoroughly in clean tap water and then purified water.

4) Make sure the sponge inside the calibration chamber is wet, and store the probe in the chamber throughout the monitoring session.

(see next page)

Under normal circumstances, teams will use the YSI-85 for the entire month of monitoring without changing the membrane or KCl solution. To check the integrity of the DO probe during the monitoring month:

1) Perform calibration per standard Streamkeepers protocol. The calibration number which appears on the calibration screen in the lower-right corner, after the step in which you enter the altitude, should be 100.0. Then let the probe sit in tap water for an hour.

2) Shake off the probe and put it back into the calibration chamber. Let the temperature and DO readings stabilize (DO% within one full percentage point and temp within 0.1°C for 30 sec.). The DO % Sat. reading should be 100% +/- 2%. If not, the membrane should be replaced (see above). (Actually, replacement is not necessary, but the probe would need to be rechecked in the field after each reading by placing it into the calibration chamber for 15 min. and then noting the DO % Sat. reading, using the above criterion.)

Between monitoring sessions, the DO probe can remain in the chamber and continue to be used, provided the integrity check is performed (see above) or the membrane is replaced.

For long-term storage of the meter (longer than a month):

1) Rinse the probe in a mild bleach solution (one capful of bleach per gallon of water).

2) Holding the probe upside-down, remove the DO membrane cap and discard the KCl solution inside. If there is no solution left under the membrane, there may have been a problem with leakage. Note which probe had this problem and check against the last time it was used in the field.

3) Rinse the cap and probe with distilled water. Shake off the water.

4) Let probe and cap air dry.

5) Replace the cap, without fluid, to protect the probe from dust.

6) Store the probe dry, outside of the calibration chamber. Put tape over the calibration chamber opening to keep the sponge from falling out.