PAR
Photosynthetic light
Measure PAR across 400–700 nm at the exact point you want to evaluate.
Underwater PAR + UVA Meter
Measure the light your corals actually receive.
PAR can change dramatically across the same reef tank. AH-Reef measures underwater PAR and UVA, shows R/G/B balance, and records up to 99 points—so coral placement is based on real data, not guesswork.
✓ Built for reef LEDs
✓ Waterproof probe
✓ In-tank mapping
PAR + UVAOne handheld reef-light tool
400–700 nmPAR measurement
UVAIrradiance data
R / G / BSpectral balance
99 PointsHold & record
IECFUnderwater correction
The problem
Your reef does not receive one PAR number.
A fixture specification—or a reading from an online video—cannot tell you what reaches every coral. Depth, horizontal position, rockwork, shadows, and mounting height all change the light at coral level.
1
Find hidden low-light zones
Measure behind rockwork, near edges, and below overhangs.
2
Identify high-PAR hotspots
Check the center and upper rockwork before placing sensitive corals.
3
Make repeatable decisions
Use the same position and depth to compare lighting changes accurately.
The solution
Measure where the coral lives—not above the tank.
Place the waterproof sensor at the exact depth and location you want to evaluate. AH-Reef displays PAR and UVA together, making it easier to map the real lighting environment inside your aquarium.
1
Place the sensor
Measure at sand bed, mid-level, or upper rockwork.
2
Record the point
Use HOLD and RECORD to store up to 99 locations.
3
Tune and place
Adjust the fixture or choose a better coral position.
More useful data
More than a basic PAR meter.
AH-Reef combines the measurements reef keepers use to understand intensity, exposure, spectral balance, and tank-wide distribution.
UV
UVA irradiance
See UVA alongside PAR instead of evaluating reef lighting from PAR alone.
RGB
R/G/B balance
Use live red, green, and blue data to understand fixture channel balance.
99
Tank-wide mapping
Freeze and store up to 99 points to document hot spots and shadows.
Confidence before purchase
See the test—not just the claim.
AH-Reef is checked in a controlled aquarium-light setup using a reference sensor under the same light and measurement conditions. Watch the underwater side-by-side comparison below.
Same light. Same water depth. Same sensor position. Closely aligned readings.
Why UVA matters
See more than PAR.
PAR measures photosynthetically active light, but it does not describe every part of a reef fixture’s output. UVA data adds another layer of visibility when you compare settings, acclimate corals, or evaluate total light exposure.
A
Compare lighting programs
See how UVA changes when you adjust violet and UV channels.
B
Avoid blind adjustments
Use measured data instead of relying only on visual brightness.
C
Evaluate spectral balance
Review UVA together with PAR and R/G/B values.
Practical reef workflow
Turn scattered readings into a useful light map.
Record consistent points across the tank, then use the pattern—not a single number—to guide fixture tuning and coral placement.
Questions reef keepers ask
Know what you are measuring.
Is AH-Reef designed to measure LED aquarium lights?
Yes. AH-Reef is designed for reef and aquarium lighting, including LED fixtures. For meaningful comparisons, keep the light settings, mounting height, water depth, sensor angle, and horizontal position the same.
Why can my reading differ from a number shown in an online video?
PAR is highly position-dependent. A center reading, an edge reading, a different channel program, or a different sensor depth can produce very different results even with the same fixture model.
What is IECF?
IECF is the Immersion Effect Correction Factor. When selected, it applies an underwater correction for measurement methods that account for the sensor’s immersion response.
Can I map multiple points across my tank?
Yes. Use HOLD and RECORD to capture up to 99 readings as you move across different depths and coral positions.
Is the sensor suitable for underwater measurement?
Yes. The waterproof probe is designed for aquarium submersion so readings can be taken at coral level.
Stop guessing
Map your reef before moving your corals.
Measure PAR, UVA, and spectral balance at the locations that matter—inside your tank.