Lab-Grade Instruments Designed Specifically For Growers
Lab-Grade Instruments Designed Specifically For Growers
Trouble
Reason
How to fix
Cannot calibrate
Incorrect calibration order
Power on the tester, calibrate pH 7 first, then pH 4. After pH 4 is calibrated,
if you want to calibrate pH 7 again, you need to reboot the tester.
Poor quality standard solutions
Replace with fresh and clean standard calibration solutions made by
legitimate scientific instrument manufacturers.
Contaminated probe
Clean the probe with Apera’s cleaning solution or detergent water.
Aged probe
Replace the probe.
Dried-out probe
Soak the probe in the 3M KCL soaking solution for at least 1 hour.
Probe is not fully submerged in the
solution
Make sure the probe is fully immersed in the solution at least 1 inch deep.
Air bubbles around the sensor
Make a quick stir in the solution to remove air bubbles.
Reading is always slowly
changing, won’t stabilize.
Contaminated probe
Clean the probe with Apera’s cleaning solution or detergent water.
Clogged junction
Clean the probe with Apera’s cleaning solution, then soak it in 3M KCL
soaking solution overnight.
Aged probe
Replace the probe.
Testing pH of low iconic strength
solutions like tap water, drinking water,
RO water
Be patient, wait for 2-5 minutes to reach a fully stabilized reading. If still not
stabilizing, add 1ml of 3M KCL solution to 1000ml of test solution.
Display similar readings in any
solutions or always display 7.0 pH
Broken probe
If you don’t find any visible damage of the probe and it’s within the 1-year
probe warranty, contact your point of purchase for warranty fulfillment;
If there is visible damage or the probe is more than 1-year old, replace the
probe.
Reading keeps jumping
Probe is not fully submerged in the
solution
Make sure the probe is fully immersed in the solution at least 1 inch deep.
Air bubbles around the sensor
Make a quick stir in the solution to remove air bubbles.
Probe is not properly connected or the
pin connector is broken.
Check the probe’s connector, make sure it’s not broken and is correctly
connected. Align the probe and instrument correctly before plugging in.
Never force it.
Ensure that the probe connector is not exposed in the air too long.
Calibration is successful, but
reading is not accurate
Aged probe
Replace the probe.
Air bubbles around the sensor
Make a quick stir in the solution to remove air bubbles.
Clogged junction
Clean the probe with cleaning solution, then soak it in 3M KCL soaking
solution overnight
Comparison with other testers, test
strips, or drop tests
To compare with other testers, make sure to perform a 2-point calibration
for all testers in the same standards, then test a 3
rd
point. Whichever gives
more accurate reading in the 3
rd
point standard is the most accurate one.
Test strips or drop tests’ accuracy is not comparable to pH meters’.
① Pull up the battery cap (might take some force).
② Slide the battery cover along the OPEN arrow to open the cover.
③ Open the battery cover.
④ Insert the batteries (ALL POSITIVE SIDES FACING UP).
⑤ Press down the battery cover and hold it.
⑥ Slide the battery cover along the LOCK arrow to lock the cover.
⑦ Close the battery cap. Make sure to push it all the way down.
The tester’s waterproof rating may be compromised if the battery cap is not tightly closed.
Screw off the probe ring, unplug the old
probe; plug in the new probe (make sure to
align the connector's position properly), and
screw on the probe ring.
Probes don’t last forever. Every probe will eventually
age and fail even if you don't use it that often. The
typical service life of GroStar probes is 18-24 months
depending on the frequency of usage and how well
you keep it clean and properly stored.
We recommend replacing your probe at least every
18 months to ensure the best accuracy.
The nice thing about GroStar pens is that you can
just buy a replacement probe instead of a whole new
tester.
12.1
Never store the probe in pure water such as tap water, RO water, distilled water, deionized water, etc.
Out of range reminder for pH
Out of range reminder for
temperature
Out of range reminder for EC
12.2
Never use your finger to touch the glass membrane or use other material to wipe it.
12.3
Avoid testing in high (>113°F) or low temperature (<41°F) solutions as it will cause greater measurement error
and damage to the probe. Test your samples and perform calibration close to room temperature as much as
possible.
12.4
Never test oily liquids.
12.5
Make sure the battery cap is completely closed with the O-ring. Otherwise, the waterproof rating could be
compromised.
10
11
12
13
08
09
Battery Replacement
Probe Replacement
Notes
Troubleshooting Guide
