Suspended Solids Meter Reading Too Low or Zero? Malaysia
Suspended Solids Meter Reading Too Low or Zero?
A suspended-solids meter may display a result that appears lower than expected—or even zero—because of the sample, measuring bottle, procedure or instrument condition.
Before assuming that the meter is faulty, check whether particles have settled, the correct sample was collected and the instrument is being operated within its specified range.
The following troubleshooting guide applies to portable instruments such as the Qiwei SS-500B Suspended Solids Meter.
Cause 1: Suspended Particles Have Settled
Many wastewater particles do not remain evenly distributed.
Heavy particles may settle at the bottom of the collection container while the clearer water near the top is transferred into the measuring bottle.
This can produce a reading that is much lower than expected.
Recommended Action
Mix the original sample gently.
Avoid vigorous shaking.
Transfer it immediately into the measuring bottle.
Measure using consistent timing.
Repeat the test.
If particles settle very quickly, document the time between mixing and measurement.
Cause 2: The Wrong Part of the Sample Was Collected
A surface sample may contain fewer heavy particles than water collected from the middle of the flow.
Similarly, a sample taken from a stagnant corner may not represent the main process.
Recommended Action
Use a fixed and representative sampling location.
When comparing results, keep the following consistent:
Sampling point
Sampling depth
Container
Collection method
Time of testing
Process condition
Cause 3: The Sample Is Below the Practical Measuring Level
The sample may contain very little suspended material.
If the actual concentration is close to the instrument’s lower measurement capability, the reading may remain at or near zero.
The Qiwei SS-500B displays readings in 1 mg/L increments.
Customers requiring finer displayed readings at low concentrations may need to consider a lower-range or higher-resolution model, subject to the complete accuracy specification.
Cause 4: The Sample Is Not Suspended Solids
Clear water may contain dissolved substances without visible or measurable suspended particles.
A water sample can show:
High conductivity
High TDS
Dissolved salts
Chemical contamination
while still having a low suspended-solids reading.
A TDS or conductivity result should not be expected to match a suspended-solids result.
Cause 5: The Wrong Instrument Was Selected
Check whether the required parameter is:
Suspended solids in mg/L
Turbidity in NTU
TDS in ppm
Conductivity in µS/cm
Another water-quality parameter
A suspended-solids meter will not reproduce the reading from a turbidity, TDS or conductivity meter.
Cause 6: The Measuring Bottle Was Not Filled Correctly
Incorrect sample volume, leakage or positioning may affect the measurement.
Recommended Action
Follow the manufacturer’s filling instructions.
Use the correct measuring bottle.
Check that the cap and bottle are in good condition.
Keep the outside clean and dry.
Insert it correctly into the meter.
Use a consistent orientation where applicable.
Cause 7: The Bottle Is Dirty in a Way That Affects the Baseline
Dirt often causes high or unstable readings, but residue, stains or incorrect cleaning may also affect the instrument’s baseline and produce unpredictable results.
Inspect for:
Chemical film
Detergent residue
Permanent staining
Scratches
Cloudiness
Condensation
External water droplets
Rinse and clean the bottle properly before repeating the measurement.
Cause 8: The Instrument Was Zeroed Incorrectly
If the wrong blank or an unsuitable reference was used during zeroing, sample results may appear too low.
Recommended Action
Follow the manufacturer’s zeroing and calibration procedure.
Do not assume that any clear-looking liquid is suitable as a blank. Use only the required reference material or procedure.
Cause 9: Incorrect Calibration
An unsuitable standard, expired reference material or incorrect calibration step may shift the instrument response.
Check:
Correct calibration material
Reference value
Expiry date
Sample bottle condition
Calibration sequence
Instrument settings
Manufacturer instructions
Do not use a turbidity standard unless the manufacturer specifically states that it is suitable for the suspended-solids meter.
Cause 10: Strong Sample Characteristics Are Affecting the Reading
Unusual industrial samples may not behave like ordinary wastewater.
Potential influences include:
Strong colour
Oil
Foam
Floating particles
Very large particles
Rapid sedimentation
Chemical reaction
Biological material
Compare the portable result with a laboratory method when the sample composition is unusual.
Cause 11: Weak Battery or Power Problem
Unstable or insufficient power may affect instrument operation.
Check:
Battery condition
Battery installation
Battery contacts
Power adaptor
Cable connection
Display warnings
Replace batteries with the correct type when required.
Cause 12: The Optical Compartment Is Obstructed
Dust, moisture or residue inside the measuring compartment may interfere with the instrument.
Do not pour water directly into the meter or insert a wet bottle.
If liquid has entered the instrument, stop using it and arrange an inspection.
Quick Troubleshooting Test
Use this procedure to determine whether the low reading is caused by the sample or meter:
Inspect and clean both measuring bottles.
Prepare one well-mixed sample.
Fill both bottles from the same sample.
Remove air bubbles.
Clean and dry the outside surfaces.
Measure both bottles using the same timing.
Repeat each reading.
Compare with a known or laboratory-tested sample where available.
If the instrument repeatedly produces low results using a suitable reference sample, calibration or inspection may be required.
When Should You Stop Using the Meter?
Arrange further checking when:
A known reference repeatedly reads zero
Verification fails
The instrument was dropped
Water entered the meter
Different bottles produce unexplained results
Calibration cannot be completed
The meter differs significantly from reference data
The display or controls are malfunctioning
Document the problem and recent measurement history before requesting technical assistance.
About the Qiwei SS-500B
The SS-500B provides:
Measurement range: 0–500 mg/L
Displayed resolution: 1 mg/L
AC adaptor or AA-battery operation
Two measuring bottles
Portable field and indoor use
It is intended for rapid suspended-solids screening and treatment-process comparison.
Contact MTM Precision
For the Qiwei SS-500B Portable Suspended Solids Meter, troubleshooting assistance, water-quality instruments or quotation, contact:
MTM Precision Sdn. Bhd.
Professional Test & Measurement Solutions Partner in Malaysia
Website: www.mtmpre.com.my
Email: mtmpre@yahoo.com
WhatsApp: +6016-660 7346
Showroom & Service Centre
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia.
Malaysia Coverage:
Selangor, Kuala Lumpur, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kedah, Perlis, Terengganu, Sabah and Sarawak.
15 Sep 2026
