What Is the Recommended Hanging Distance for the PT8 Grow Light?

Getting the hanging distance right is one of the most critical factors in indoor growing. Too close and you risk light stress or heat damage to delicate leaves. Too far and your plants receive insufficient PPFD, leading to leggy growth, lower yields, and wasted electricity. The Koray Lighting RX-PT8 series has a clearly defined optimal distance range that balances light intensity, uniformity, and energy efficiency.

The recommended hanging distance for the PT8 series is 0.2 to 0.3 meters (approximately 8 to 12 inches) from the top of the plant canopy. This range is based on extensive testing in Koray Lighting’s 2,800 square meter facility and has been validated by commercial growers worldwide. In this article, we break down exactly why this distance range is optimal and how to adjust it for different crops and growing stages.

Frequently Asked Questions

What is the recommended hanging distance for the PT8?

Koray Lighting recommends a hanging distance of 0.2 to 0.3 meters (8 to 12 inches) from the PT8 tube to the top of the plant canopy. This distance range provides strong PPFD levels while maintaining good light uniformity across the growing area. At 0.2 meters, the PT8 V3 delivers 316 umol/m2/s, and at 0.3 meters, it delivers 210 umol/m2/s.

What PPFD does the PT8 deliver at different distances?

The PT8 V3 spectrum delivers the following PPFD values at different distances: 416 umol/m2/s at 0.15m (6 inches), 316 umol/m2/s at 0.2m (8 inches), and 210 umol/m2/s at 0.3m (12 inches). The F175 spectrum delivers 275 umol/m2/s at 0.2m and 185 umol/m2/s at 0.3m. These measurements are taken directly below the center of the tube.

Can I hang the PT8 closer than 0.2 meters?

Yes, you can mount the PT8 as close as 0.15 meters (6 inches) to the canopy. At this distance, the V3 spectrum delivers 416 umol/m2/s, which is excellent for high-light crops. However, be aware that the light spread becomes narrower at closer distances, so you may need more tubes to cover the same shelf width. Koray’s secondary optics lens helps minimize hot spots even at close range.

Can I hang the PT8 farther than 0.3 meters?

While the PT8 can technically operate at greater distances, the PPFD drops significantly beyond 0.3 meters. At distances above 0.5 meters, the light intensity may fall below the thresholds needed for healthy growth of most crops. If your setup requires a greater hanging distance, consider using a higher-output Koray product such as the G138 series or the GE35 series instead.

Does the recommended distance change for different crops?

Yes, the optimal distance varies by crop type. For seedlings and tissue culture, a distance of 0.2 to 0.5 meters is appropriate since young plants need lower light intensity. For leafy greens like lettuce and herbs, 0.2 to 0.3 meters is ideal. For fruiting crops like strawberries or peppers that need higher PPFD, keep the distance at 0.15 to 0.2 meters to maximize light delivery.

How does the PT8’s lens affect the recommended hanging distance?

The PT8 uses Koray’s proprietary secondary optics lens, which spreads light more evenly than bare LED strips. This lens design allows the PT8 to maintain good PPFD uniformity even at the recommended close distance of 0.2 meters, without creating the intense center hotspot that plagues many competing products. This is why the PT8 can be mounted closer to the canopy than many alternatives without risk of burning plant tissue.

What is the DLI (daily light integral) at the recommended distance?

At 0.2 meters with the V3 spectrum (316 umol/m2/s), running the lights for 16 hours per day delivers a DLI of approximately 18.2 mol/m2/day. This is well within the ideal range for most leafy greens (12 to 18 mol/m2/day) and suitable for many fruiting crops (18 to 30 mol/m2/day). You can adjust the photoperiod or dim the lights to fine-tune the DLI for your specific crop.

Should I adjust the PT8 distance as my plants grow taller?

Yes, as plants grow taller and the canopy rises closer to the light, you should gradually raise the PT8 tubes to maintain the recommended 0.2 to 0.3 meter distance. In vertical shelf systems, this is typically done by adjusting the shelf height or the light mounting brackets. Keeping a consistent distance ensures uniform light delivery throughout the entire growth cycle.

Why Choose Koray Lighting?

Koray Lighting has been a trusted name in horticultural lighting since 2009. With over 200 patents, a 2,800 square meter testing facility, and products exported to more than 60 countries, Koray combines deep optical engineering expertise with rigorous quality control. Every product in the RX-PT8 line undergoes comprehensive testing to ensure consistent PPFD output, reliable waterproof performance, and long-lasting durability. Whether you are setting up your first vertical farm or scaling a commercial plant factory, Koray Lighting provides the technology, support, and proven track record to help your crops thrive.

For more information about the RX-PT8 series or to request a custom lighting plan for your facility, visit www.koraylights.com.