Apera Instruments GroStar GS1 User manual

How Long Does the Coverage Last?
Apera Instruments® (Apera) warrants the GroStar™ GS1 Premium pH Pen Tester (Product) for a period of 24 months
for the instrument and 12 months for the probe from date of purchase by original purchaser or consumer. Proof of
purchase is required for the warranty to be effective (store sales receipt for Product showing model number, payment
and date of purchase). This warranty is non-transferable and terminates if the original purchaser/consumer sells or
transfers the Product a third party.
What is Covered?
Apera warrants the Product against defects in material and workmanship when used in a normal manner, in
accordance with Apera instruction manuals. If Apera is provided with valid proof of purchase (as defined above)
and determines the Product is defective, Apera may, in its sole discretion either (a) repair the Product with new or
refurbished parts, or (b) replace the Product with a new or refurbished Product.
What is NOT Covered?
This warranty does not apply to equipment, component or part that was not manufactured or sold by Apera, and shall
be void if any such item is installed on a Product. Further, this warranty does not apply to replacement of items subject
to normal use, wear and tear and expressly excludes:
• Cosmetic damage such as stains, scratches and dents
• Damage due to accident, improper use, negligence, careless operation or handling of Product not in accordance
with Apera instruction manuals, or failure to maintain or care for Product as recommended by Apera
• Damage caused by use of parts not assembled/installed as per Apera instructions
• Damage caused by use of parts or accessories not produced or recommended by Apera
• Damage due to transportation or shipment of Product
• Product repaired or altered by parties other than Apera or its authorized agents
• Product with defaced, missing or illegible serial numbers
• Products not purchased from Apera or an Apera-authorized distributor or reseller.
How Do You Get Service?
To begin a warranty claim you must return the Product to the point of purchase with valid proof of purchase.
Limitation of Liability & Acknowledgments
TO THE MAXIMUM EXTENT PERMITTED BY LAW, THIS WARRANTY AND THE REMEDIES SET OUT ABOVE ARE EXCLUSIVE
AND IN LIEU OF ALL OTHER WARRANTIES, GUARANTEES AND REMEDIES (ORAL OR WRITTEN, EXPRESS OR IMPLIED).
EXCEPT AS PROVIDED IN THIS WARRANTY AND TO THE MAXIMUM EXTENT PERMITTED BY LAW, APERA INSTRUMENTS
IS NOT RESPONSIBLE FOR SPECIAL, INCIDENTIAL OR CONSEQUENTIAL LOSS OR DAMAGES, OR ANY OTHER LOSS
OR DAMAGES RESULTING FROM SALE OR USE OF THE PRODUCT, OR BREACH OF WARRANTY, HOWEVER CAUSED,
INCLUDING DAMAGES FOR LOST PROFITS, PERSONAL INJURY OR PROPERTY DAMAGE.
IT IS UNDERSTOOD AND AGREED BY CONSUMER UPON PURCHASE OF A PRODUCT THAT, EXCEPT AS STATED IN THIS
WARRANTY, APERA INSTRUMENTS IS NOT MAKING AND HAS NOT MADE ANY EXPRESS OR IMPLIED WARRANTY OR
OTHER REPRESENTATION REGARDING THE PRODUCT, AND DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE TO THE EXTENT PERMITTED BY LAW. ANY WARRANTIES WHICH ARE IMPOSED BY
LAW AND CANNOT BE DISCLAIMED ARE HEREBY LIMITED IN DURATION TO THE PERIOD AND REMEDIES PROVIDED IN
THIS WARRANTY.
SOME JURISDICTIONS (STATES OR COUNTRIES) DO NOT ALLOW EXCLUSION OR LIMITATION FOR INCIDENTIAL
OR CONSEQUENTIAL DAMAGES, OR LIMITATION ON HOW LONG AN IMPLIED WARRANTY LASTS, SO THE ABOVE
LIMITATION OR EXCLUSION MAY NOT BE APPLICABLE. IF ANY PROVISION OF THIS WARRANTY IS JUDGED TO BE
ILLEGAL, INVALID OR UNENFORCEABLE, THE REMAINING PROVISIONS OF THE WARRANTY SHALL REMAIN IN FULL
FORCE AND EFFECT.
Governing Law; Authority
This warranty is governed by the laws of the state of country where Product is purchased, without regard to its choice
of law principles. Except as allowed by law, Apera does not limit or exclude other rights a consumer may have with
regard to the Product. No Apera distributor, employee or agent is authorized to modify, extend or otherwise change
the terms of this warranty.
Warranty
Address: 6656 Busch Blvd, Columbus Ohio 43229
Tel: [phone]
Email: [e-mail]
Website: aperainst.com
®
GS1 Premium pH Pen Tester
AI11010
User Guide
®
aperainst.com
14

Lab-Grade Instruments Designed Specifically For Growers Lab-Grade Instruments Designed Specifically For Growers
page
Main Features
Preparation Before First Use
pH Calibration
pH Measurement
Other Functions
Probe Cleaning
Probe Storage
Battery Replacement
Probe Replacement
Notes
Troubleshooting Guide
Technical Specs
Accessories
Warranty
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Thank you for choosing the Apera GroStar™ GS1 Premium pH Pen Tester. This premium pen has been designed
specifically for the horticultural market. Since 1991, Apera instruments has been dedicated to providing hi-tech,
accurate, lab-grade instruments and sensors. GroStar's intelligent design reduces the guesswork so you can easily
manage your crops success.
• Premium pH probe with double-junction and sensor shield, increased reliability and durability.
• Easy to use design and quick two point calibration adjustment.
• 3-Color backlit LCD screen gives you clear readings in different modes even in dark enviroment.
• Durable structure, IP67 waterproof rating, powered by AAA batteries.
• The pH probe is replaceable, so you don't have to discard the entire pen when the probe reaches its end of life.
3-Color LCD Screen
stands for stabilized reading
• White for measurement mode
• Green for calibration mode
• Red for calibration error
L/M/H stands for successful
calibration: Lis pH 4, Mis pH 7, H
is pH 10. The icon(s) will disappear
after 30 days to remind you for re-
calibration.
• Water droplets are added
during production to maintain
the moisture of the probe.
This is normal practice and
should not be attributed to
used product.
• The fill line shows the level
to which you should pour the
soaking solution or sample
solution.
• For details of probe storage,
see Section 7.
Short Press Long Press
Power off
Start
calibration
Switch
between
°F and °C
Sensor Shield
Protects the sensitive pH glass membrane from
accidental damage. Remove it when cleaning
the pH sensor.
Premium pH Probe
• Built with low-resistance lithium glass membrane
with double-junction and blue gel electrolyte,
ensuring accuracy and durability.
• The repaceable probe saves money in the long run.
01
02
Main Features
Contents
Probe Cap
01
02
03
04
05
06
07
08
09
10
11
12
13
14
1. Power on
2. Manual hold
Press again to cancel hold.
In measurement
mode, press to turn
on/off the backlight.
In calibration mode,
press to cancel
calibration.

Lab-Grade Instruments Designed Specifically For Growers Lab-Grade Instruments Designed Specifically For Growers
02
2.4 If you find the probe cap is dried out, soak the probe in 3M KCL soaking solution
for 5 minutes before use.
2.5 If the tester hasn’t been used for a long time (over 1 month), please soak the
probe in the 3M KCL soaking solution for at least 1 hour, then calibrate it before
measurement begins.
03
Preparation Before First Use
3.1 Power on the pen and remove the probe cap.
Always calibrate 7.00 pH first.
3.2 Rinse the probe with clean water and shake-dry, then submerge it in the
7.00 pH standard buffer; shake the probe up and down in the solution
for a few seconds, then let it stand.
3.3 Hold until screen turns green. The tester starts the automatic
calibration. Wait for "Good" to show up (in 10-15 seconds), indicating
the calibration is completed, then the tester returns to measurement
mode.
Short press any key while calibrating (in green screen) to cancel calibration
and return to measurement.
7.00
pH
7.00
pH
03
04
pH Calibration
2.1 Pull out the battery insulation slip, and take off the probe cap.
2.2 Rinse off the probe in clean water, then shake off excess water.
2.3 Perform a 2-point calibration at pH 7 and pH 4. For calibration tutorial, refer to Section 3.
3.4 icon will show up on the lower left corner of the screen indicating the
tester is successfully calibrated. Repeat Step 3.2 to 3.3 to calibrate pH 4
using 4.00 pH buffer, then will show up next to .
You can continue to calibrate pH 10 by repeating Step 3.2 to 3.3 using
10.01 pH buffer (sold separately), then will show up to the right of .
3.5 / / will disappear in 30 days after calibration, reminding you
to re-calibrate the tester. We recommend calibrating pH at least once a
month to ensure accuracy. If you feel like the accuracy might be off, simply
test the standard buffers (make sure the buffers are fresh and clean). If a
discrepancy is found, then it’s time to calibrate again.
Calibrating pH 10 is usually not necessary unless your estimated target pH is
greater than 8.0 pH.
Always perform at least a 2-point pH calibration to ensure accuracy. Start
with 7.00 pH, followed by 4.00 pH immediately. If you happened to turn
off the pen before calibrating 4.00 pH, you need to start with 7.00 pH again
after rebooting the pen, then 4.00 pH.
3.6 If the calibration fails, the screen will turn red. For details, refer to Section
11 Troubleshooting Guide.

Lab-Grade Instruments Designed Specifically For Growers Lab-Grade Instruments Designed Specifically For Growers
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Other Functions
05
or
6.1 The tester is only as accurate as the probe is clean. Always thoroughly rinse off the probe before and after each
measurement with clean water in a container or with a wash bottle.
6.2 For tough contaminants, remove the sensor shield, soak the probe in Apera’s cleaning solution or detergent
water for 30 minutes. Then use a soft brush to remove the contaminants. Afterwards, soak the probe in 3M
KCL soaking solution for at least 1 hour. Rinse it off, then re-calibrate the tester before using again. These
cleaning tools can be found in the Probe Care Kit (see Section 13).
Probe Cleaning
06
06
Probe Storage
07
Battery Replacement
08
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.
04
4.1 Power on and remove the probe cap.
4.2 Rinse the probe with clean water and shake off excess water.
4.3 Fully submerge the probe into your solution at least 1 inch deep, make a
quick stir to remove potential air bubbles around the probe.
4.4 Hold the pen and wait for the reading to stabilize ( stays on screen),
then record the reading.
4.5 Thoroughly rinse off the probe with clean water, then close the probe cap.
04
pH Measurement
5.1 If necessary, you can manually hold (lock)
the reading by short pressing . Press
it again to cancel the hold.
5.3 The tester will automatically power
off if there is no operation within
10 minutes. If you want to turn off
the Auto. Power Off function, power
off the tester, and then hold for
5 seconds until you see Auto off.
Then it will power on and go to
measurement mode automatically.
5.2 Long press to switch temp. unit
between °F and °C.
If you find white crystals inside or outside the probe cap, it is perfectly normal.
It is the 3M KCL soaking solution that crystalizes over time by its nature. Just
rinse them off and add in new soaking solution. This chemical is not poisonous
nor dangerous, and the probe’s performance will not be affected at all.
7.1 Under regular usage (daily or weekly use), make sure there are several
drops of 3M KCL soaking solution in the probe cap, and tightly
close the cap with the O-ring.
7.2 For long-term storage (you are not going to use the product for a while), add 3M KCL
soaking solution to the Fill line in the probe cap and store the probe in it. Close on the
probe cap tightly with the O-ring.

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 solutionsmade 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 1inch 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 afully stabilizedreading. 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 1inch 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 3rd point. Whichever gives
more accurate reading in the 3rd point standard is the most accurate one.
Test strips or drop tests’ accuracy is not comparable to pH meters’.
07
Screw off the probe ring, unplug the old probe; plug in the new probe (make sure to align
the connector's position properly), then screw on the probe ring.
pH probes don’t last forever. Every pH probe will eventually age and fail even if you don't
use it that often. The typical service life of GroStar pH 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.
10.1 Never store the probe in pure water such as tap water, RO water, distilled water, or
deionized water. Doing so will cause damage to the pH probe.
10.2 Never use your finger to touch the glass membrane or use other material to rub it.
Doing so could generate static electricity and cause measurement errors.
10.3 Avoid testing in high (>113°F) or low (<41°F) temperature solutions as it will cause greater
measurement error and potential damage to the probe. Test your samples and perform
calibration close to room temperature as much as possible.
10.4 Never test oily liquids.
10.5 Make sure the battery cap is completely closed with the O-ring. Otherwise, the waterproof
rating could be compromised.
Probe Replacement
Notes
09
10
08
Troubleshooting Guide
11
Out of range reminder for pH Out of range reminder for temperature

Lab-Grade Instruments Designed Specifically For Growers Lab-Grade Instruments Designed Specifically For Growers
Range 0.0 to 14.0 pH,
0 to 50˚C (32 to 122˚F)
Resolution 0.1 pH, 0.1˚F/0.1˚C
Accuracy ±0.1 pH,
±1˚C/±1˚F
Temperature Compensation Automatic
pH Calibration Automatic 1 to 3 points (7/4/10)
*pH 10.01 solution sold separately
Unit pH, ˚F, ˚C
Power supply 4-AAA alkaline batteries
Backlight White (measurement); Green (calibration); Red (errors)
Reading hold Manual
Warranty Two years for the instrument, one year for the probe
pH probe Low-resistance lithium glass membrane, double-junction,
blue gel electrolyte
Successful calibration indicators M (7.00 pH), L (4.00 pH), H (10.01 pH)
Low battery reminder
Waterproof rating IP67
Reading stabilization icon
What’s in the box GS1 Premium pH Pen Tester, pH 7.00/4.00 (50mL each), 3M
KCL storage solution (10ml), user manual, lanyard.
09
Technical Specs
12
pH buffer kit (4&7, 8oz. each) pH buffer kit (4,7&10, 8oz. each)
Replacement Probes
GS1-E pH Probe GS2-E Soil pH Probe
Probe Care Kit
includes 3M KCL storage solution
(4oz.), cleaning solution (8oz.),
a CalPod solution organizer, a probe
cleaning brush, and a wash bottle
10
Accessories
13
GS1 pH Pen
Lanyard
Soaking
Solution
7.00 pH
Solution
4.00 pH
Solution
What's in the box