ISO 7027-compliant turbidity measurement from 0–1000 NTU, field-ready and IP67-sealed.
The Apera Instruments TN400 (AI481) is a portable turbidity meter built around an infrared LED (860 ± 30 nm) and a 90° nephelometric measurement method fully compliant with ISO 7027 and DIN EN 27027. It delivers defensible, repeatable turbidity readings across a 0–1000 NTU range — in the reservoir room, at the RO station, or out in the field.
The Apera TN400 (SKU: AI481) is a field-grade portable turbidity meter designed for operators who need ISO-compliant turbidity data outside of a fixed lab setup. The meter uses an infrared LED light source at 860 ± 30 nm and measures the 90° scattered light signal from a sample — the nephelometric method specified by ISO 7027 and DIN EN 27027. This is the same methodology required for regulated drinking water analysis and increasingly referenced in cannabis and hemp cultivation compliance documentation.
The unit covers a 0–1000 NTU range with three auto-selected sub-ranges (0.01–19.99, 20.0–99.9, and 100–1000 NTU), giving it the resolution to detect fine particulate in treated source water and the headroom to assess visibly turbid process water or runoff. Accuracy is rated at ≤ ±2% of reading plus stray light, with repeatability of ≤ ±1% or 0.02 NTU — numbers that hold up under audit.
Any licensed cultivation operation running reverse osmosis, UV sterilization, or recirculating hydroponic systems needs consistent turbidity monitoring at multiple points in the water chain — municipal source, post-filtration, reservoir, and drain-to-waste or recycle streams. High turbidity upstream reduces UV dose effectiveness and increases biofilm risk in drip lines and reservoir walls. The AI481 gives cultivation staff a fast, portable way to confirm water quality at each stage without sending samples to an outside lab.
It is equally useful at harvest and post-processing stages where water clarity affects extraction efficiency and product quality. Beverage and infused product operations — a growing part of the licensed cannabis segment — already rely on nephelometric turbidity meters as a standard QC checkpoint. The TN400's IP67 housing and battery operation (4 AA cells included) mean it can move from a mechanical room to a processing suite to an outdoor collection point without special accommodations.
Two measurement modes adapt the meter to the sample at hand. Normal Mode captures a single rapid reading for routine spot checks. Average Mode runs 10 consecutive measurements automatically and returns the mean — the right call for samples with visible settling or flow-induced fluctuation, which is common in actively aerated reservoirs. Switching between modes is handled through the on-screen interface without navigating multi-level menus.
The TFT color display uses distinct screen colors for measurement (blue) and calibration (green), with on-screen graphic and text guides that walk through each step. The kit ships with five AMCO Clear® high-molecular-weight polymer calibration standards (0.0, 20, 100, 400, and 800 NTU) that are EPA-approved for drinking water turbidity calibration, NIST-traceable, non-toxic, and stable in suspension. Standards carry a one-year shelf life. The housing is rated IP67 — fully dust-tight and submersion-resistant — and the instrument is CE, RoHS, and FCC certified.
Water quality documentation is becoming a standard expectation in state cannabis audits and in Good Agricultural Practices frameworks that multi-state operators are building toward. Having an ISO 7027-compliant meter on-site means turbidity data is generated with a traceable method — not just a rough visual check — and can be logged into an SOP-backed QC record. The AI481 is portable enough to be shared across shifts and facility zones without assigning it to a fixed workstation.
For operations using nutrient-film or recirculating DWC systems, turbidity is also a real-time proxy for biological load and filter performance. A trend toward higher readings between filter changes is actionable data; a single point-in-time check with a non-calibrated sensor is not. The TN400's included calibration standards, two-year limited warranty from Apera Instruments, and straightforward recalibration routine make it a practical, maintain-in-house tool rather than a send-out instrument.
| SKU | AI481 |
| Model | TN400 |
| Measurement Range | 0–1000 NTU (auto-range: 0.01–19.99 / 20.0–99.9 / 100–1000 NTU) |
| Light Source | Infrared LED, 860 ± 30 nm |
| Measurement Method | 90° nephelometric (ISO 7027 & DIN EN 27027 compliant) |
| Accuracy | ≤ ±2% of reading + stray light |
| Repeatability | ≤ ±1% or 0.02 NTU, whichever is greater |
| Measurement Modes | Normal (single reading) / Average (10-reading auto-mean) |
| Display | TFT full-color with graphic & text operation guides; color-coded by mode |
| Ingress Protection | IP67 |
| Power | 4 × AA batteries (included) |
| Calibration Standards Included | 5-point AMCO Clear® polymer standards: 0.0, 20, 100, 400, 800 NTU — EPA-approved, NIST-traceable |
ISO 7027 specifies the exact light source wavelength (near-infrared, 860 nm) and scattering angle (90°) used for turbidity measurement. Using a compliant method means your turbidity readings are generated the same way regulatory and laboratory instruments generate them — making your QC data defensible in an audit and comparable to third-party lab results. A non-compliant white-light meter can read the same sample significantly differently, especially in colored solutions like nutrient feeds.
Normal Mode takes a single measurement and displays it immediately — appropriate for clear, stable samples during routine spot checks. Average Mode runs 10 consecutive readings automatically and returns the mean value. Use Average Mode when the sample has visible particulate settling, when the reservoir is actively aerated and causing optical fluctuation, or when you need the most defensible data point for a QC record.
The included AMCO Clear® polymer standards have a guaranteed one-year shelf life from the date of manufacture. Unlike formazin standards, they are stable in suspension and do not settle, making them practical for field calibration kits that sit on a shelf between uses. Replacement standard sets are available separately through HSC.
Yes. The 0–1000 NTU range and infrared light source are well-suited to nutrient solutions, RO permeate, reservoir water, and drain-to-waste samples. Note that deeply colored solutions (e.g., heavily loaded organic nutrient mixes) can introduce some interference in any turbidimeter — the TN400's infrared source minimizes color-based interference compared to white-light instruments, but is not fully immune in extreme cases. For most standard hydroponic feed solutions and source-water applications, it performs reliably.
IP67 means the housing is fully dust-tight and rated for temporary immersion up to 1 meter for 30 minutes. In practical cultivation terms: splashes, humid mechanical rooms, wet floors, and rinse-station environments are all within spec. It is not rated for continuous submersion or pressure washing. The battery compartment is sealed with a waterproof hatch that requires the included small screwdriver to open.
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