PAR Estimator
Estimate PAR at substrate depth in your aquarium.
Light Intensity (PAR) Estimator
Estimate PAR at substrate depth
Formula
PAR at depth = Surface PAR × e^(-k × depth)How to Use
- 1Enter light specifications — Input your light fixture wattage and type (LED, T5, etc.).
- 2Enter tank depth — Measure the distance from the light to the substrate in inches.
- 3Review PAR estimate — See the estimated PAR value at substrate level.
- 4Match to plant needs — Low light plants need 20-40 PAR, medium 40-80, high light 80+ PAR.
Frequently Asked Questions
What PAR do aquarium plants need?
Low light plants (Anubias, Java fern): 20-40 PAR. Medium (Amazon sword, Crypts): 40-80 PAR. High (carpet plants, red plants): 80-150+ PAR.
Does water depth affect PAR?
Yes, water absorbs light significantly. PAR drops roughly 50% for every 12 inches of water depth.
How do I measure PAR in my tank?
Use a PAR meter (like Apogee MQ-500) if available. Otherwise, this estimator provides a reasonable approximation.
More PAR means more algae?
High PAR without adequate CO2 and nutrients can fuel algae growth. Balance all three factors for best results.