Apera Instruments GroStar GS4 User manual

GroStar™

GS4 Premium pH/EC Pen Tester

User Manual

APERA INSTRUMENTS (Europe) GmbH

www.aperainst.de

1 
 
Content 
1Main Features ................................................................................................................ 1 
2Preparation Before First Use .......................................................................................... 3 
3pH Calibration................................................................................................................. 3 
4pH Measurement............................................................................................................ 5 
5EC Calibration................................................................................................................ 5 
6EC/500ppm/700ppm Measurement................................................................................ 6 
7Other Functions.............................................................................................................. 6 
8Probe Cleaning............................................................................................................... 7 
9Probe Storage................................................................................................................ 7 
10 Battery Replacement...................................................................................................... 8 
11 Probe Replacement........................................................................................................ 8 
12 Notes.............................................................................................................................. 8 
13 Troubleshooting Guide ................................................................................................... 9 
14 Technical Specs............................................................................................................10 
15 What’s in the box...........................................................................................................11 
16 Accessories...................................................................................................................11 
17 Warranty........................................................................................................................12 
 
Thank  you  for  choosing  the  Apera GroStar™  GS4  Premium  pH  EC  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. 
 
1 Main Features 
•Premium combo pH/EC probe measures pH, EC, ppm (500/700) all-in-one unit with 
minimal maintenance. 
•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 
environment. 
•Durable structure, IP67 waterproof rating, powered by AAA batteries.
•The 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

•White for measurement mode

•Green for calibration mode

•Red for calibration error

stands for stabilized

reading

L/M/H stands for successful

calibration: L is pH 4, M is pH 7

or 2.77 EC, H is pH 10. The icon(s)

will disappear after 30 days to

remind you for re-calibration.

Probe Cap

•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 9.

Premium pH • EC Combo Probe

•Upgraded double-junction blue pH

sensor, increased durability and easier to

use.

•Titanium alloy conductivity sensor, highly

accurate and requires minimal

maintenance.

•The probe is replaceable, saving money in

the long run.

Short Press

Long Press

1. Power on

2. Manual hold

Press again to

cancel hold.

Power off

measurement

mode, press to

turn on/off the

backlight.

Start

calibration

Switch mode:

pH→EC→500p

pm →700ppm

Switch

between °F

and °C

Sensor Shield

Protects the sensitive pH glass

membrane from accidental damage.

Remove it when cleaning the pH sensor.

2 Preparation Before First Use

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 Calibrate pH and EC. For calibration tutorial, refer to Section 3 and Section 4.

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

3 pH Calibration

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 off excess water,

then submerge it in the 7.00 pH standard buffer; shake the probe

up and down in the solution for a few seconds and let it stand.

3.3 Hold until screen turns green. The pen starts automatic

calibration. Wait for "Good" to show up (in 10-15 seconds),

indicating the calibration is completed, then the pen returns to

measurement mode.

Short press any key while calibrating (in green screen) to cancel

calibration and return to measurement.

3.4 icon will show up on the lower left corner of the screen

indicating the pen 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 .

Calibrating pH 10 is usually not necessary unless your estimated target pH is greater than 8.0

pH.

3.5 / / will disappear in 30 days after calibration,

reminding you to recalibrate 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.

3.6 If the calibration fails, the screen will turn red. For details, see

Section 13 Troubleshooting Guide.

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.

4 pH Measurement

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 the 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.

5 EC Calibration

5.1 Power on and remove the probe cap. Press to switch to EC

measurement mode. Rinse the probe with clean water and

shake-dry, then submerge it in the 2.77 EC standard solution;

shake the probe in the solution up and down for a few seconds

to remove potential air bubbles, then let it stand.

5.2 Hold until screen turns green. The pen starts automatic

calibration. Wait for "Good" to show up (in 10-15 seconds),

indicating the calibration is completed, then the pen returns to measurement mode.

Short press any key while calibrating (in green screen) to cancel calibration and return to

measurement.

5.3 icon will show up on the lower left corner indicating the tester

is successfully calibrated. will disappear in 30 days after

calibration, reminding you to re-calibrate EC. We recommend

calibrating the EC once every month to ensure the accuracy. If

you feel like the accuracy might be off, simply test the standard

solution (make sure the standard is fresh and clean). If the reading is greater than 2.8

EC or smaller than 2.7 EC, then it’s time to calibrate again.

5.4 If the calibration fails, the screen will turn red. For details, see

Section 13 Troubleshooting Guide.

6 EC/500ppm/700ppm Measurement

6.1 Power on and remove the probe cap.

6.2 Rinse the probe with clean water and shake off excess water.

6.3 Submerge the probe into the solution, make a quick stir to remove

potential air bubbles around the sensor. Hold still and wait for the

reading to stabilize ( stays on the screen), then record the

reading.

6.4 Short press to switch from EC → 500ppm → 700ppm

6.5 Thoroughly rinse off the probe with clean water.

What is EC and its relation to 500ppm & 700ppm?

EC (electrical conductivity) is a measure of the nutrients in the solution. Low conductivity

implies a low nutrient concentration, which usually results in nutritional deficiencies and slow

growth rates of your plants.

A higher conductivity is more food for your plants. However, be careful of very high levels as

delicate plants, cuttings, and seedlings can experience fertilizer burn if the conductivity is

excessively high.

EC, 500ppm, and 700ppm are simply different units preferred by different markets. 500ppm

and 700ppm both originate from EC. Therefore, using EC to compare and analyze test result

is the safest way and will minimize confusion. Here is how they convert to each other:

1.0 (EC) = 500ppm (500ppm) = 700ppm (700ppm)

2.6 (EC) = 1300ppm (500ppm) = 1820ppm (700ppm)

3.5 (EC) = 1750ppm (500ppm) = 2450ppm (700ppm)

7 Other Functions

7.1 If necessary, you can manually hold (lock) the reading by short pressing . Press it

again to cancel the hold.

7.2 Long press to switch temp. unit between °F and °C.

7.3 The tester will automatically power off if there is no operation

within 10 minutes. If you want to turn off/on the Auto. Power Off

function, power off the tester, and then hold for 5 seconds

until you see Auto Off or Auto On. Then it will power on and go

to measurement mode automatically.

8 Probe Cleaning

8.1 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.

8.2 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 1 hour. Rinse

it off, then re-calibrate the tester before using again.

9 Probe Storage

9.1 Under regular usage (daily or weekly use), make sure there are several

drops 3M KCL soaking solution in the probe cap, and tightly close the cap

with the O-ring.

9.2 For long-term storage (you are not going to use the product for more than a

month), add 3M KCL soaking solution to the Fill line in the cap and store

the probe in it. Close the probe cap tightly with the O-ring.

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.

10 Battery Replacement

①Pull up the battery cap (might take some force).

②Slide the battery cover along the OPEN arrow to open the cover.

③Open the battery cover.

④Insert the batteries (ALL POSITIVE SIDES FACING UP).

⑤Press down the battery cover and hold it.

⑥Slide the battery cover along the LOCK arrow to lock the cover.

⑦Close 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.

11 Probe Replacement

•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 Notes

12.1 Never store the probe in pure water such as tap water, RO water, distilled water,

deionized water, etc.

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/ 45°C) or low temperature (<41°F/ 5°C) 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.

13 Troubleshooting Guide

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

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.

Other manuals for GroStar GS4

This manual suits for next models

Table of contents

Other Apera Instruments Test Equipment manuals

Apera Instruments

Apera Instruments GroStar GS1 User manual

Apera Instruments

Apera Instruments ORP60-Z User manual

Apera Instruments

Apera Instruments GroStar GS3 Premium User manual

Apera Instruments

Apera Instruments LabSen 753 User manual

Apera Instruments

Apera Instruments PC60 User manual

Apera Instruments

Apera Instruments PH20 User manual

Apera Instruments

Apera Instruments LabSen 231 User manual

Apera Instruments

Apera Instruments Salt20 User manual

Apera Instruments

Apera Instruments PH20 User manual

Apera Instruments

Apera Instruments PH60 User manual

Apera Instruments

Apera Instruments Premium ORP5 User manual

Apera Instruments

Apera Instruments PC60 User manual

Apera Instruments

Apera Instruments PH60-E User manual

Apera Instruments

Apera Instruments SX620 User manual

Apera Instruments

Apera Instruments 28APE190027 User manual

Apera Instruments

Apera Instruments LabSen 241-6 User manual

Apera Instruments

Apera Instruments Premium Series User manual

Apera Instruments

Apera Instruments 60-Z Series User manual

Apera Instruments

Apera Instruments 201T-F User manual

Apera Instruments

Apera Instruments EC20 User manual

Apera Instruments

Apera Instruments PH60F-E User manual

Apera Instruments

Apera Instruments GroStar GS3 Premium User manual

Apera Instruments

Apera Instruments PH60 User manual

Apera Instruments

Apera Instruments SX630 User manual

Popular Test Equipment manuals by other brands

SMART

SMART KANAAD SBT XTREME 3G Series user manual

Agilent Technologies

Agilent Technologies BERT Serial Getting started

Agilent Technologies

Agilent Technologies N3280A user guide

Vernier

Vernier Go Direct Voltage manual

Lifeloc

Lifeloc R.A.D.A.R. quick start guide

Fluke

Fluke T5-600 Service information

Mercury

Mercury TSL01 user manual

MAHA

MAHA MBT Series Original operating instructions

Fuji Electric

Fuji Electric P-61 instruction manual

ETC

ETC SealerAtor user manual

Skyfine

Skyfine ETHYWAY V2 user manual

Appion

Appion G5 Twin Operation manual

PCB Piezotronics

PCB Piezotronics 8159-0112A Installation and operating manual

BW Technologies

BW Technologies MicroDock II user manual

Sun Nuclear

Sun Nuclear 1027 user guide

Biomark

Biomark HPR LITE READER user manual

Hioki

Hioki 3169-20 instruction manual

Ashcroft

Ashcroft ATE-100 operating manual