When designing an indoor growing system with LED tube lights, one of the most common questions growers ask is: what exactly is the difference between the RX-PT8 and the RX-PT8T? Both belong to Koray Lighting’s PT8 product family, but they differ in optical design, light output, waterproof rating, and ideal application scenarios. This guide breaks down every meaningful difference so you can make an informed decision for your commercial or hobby grow setup.

Core Design Philosophy

The RX-PT8 is a straightforward LED grow tube designed for general-purpose indoor cultivation. It uses high-quality LEDs without an additional optical lens, providing a wide, even light distribution that works well for basic leafy green production and seedling propagation. Its simple design makes it an economical choice for growers who need broad coverage without intense light concentration.

The RX-PT8T, on the other hand, incorporates Koray’s proprietary secondary optical technology. A specially engineered lens sits over the LED array, concentrating the photon output into a tighter beam pattern. This results in significantly higher PPFD (Photosynthetic Photon Flux Density) at the canopy level, which translates to faster growth rates and higher yields for light-demanding crops.

Koray PT8 LED grow tubes in production facility

PPFD Output Comparison

The most significant practical difference between the two models lies in their PPFD performance. At a standard mounting distance of 0.2 meters, the RX-PT8T with V3 spectrum delivers 316 μmol/m²/s, while the non-lens PT8 with F4K spectrum delivers only 196 μmol/m²/s at the same distance. That is a 61% increase in photosynthetically active radiation reaching your plants.

Even when comparing the same spectrum type, the lens-equipped PT8T consistently outperforms. The PT8T-F175 at 0.2m delivers 275 μmol/m²/s, and the PT8T-V3 pushes it to 316 μmol/m²/s. This means fewer tubes are needed to achieve target PPFD levels, reducing both equipment cost and energy consumption per square meter of growing area.

Waterproof Rating and Durability

Both the RX-PT8 and RX-PT8T carry an IP66 waterproof rating, meaning they can withstand powerful water jets and are fully protected against dust ingress. This makes both models suitable for humid environments typical of hydroponic systems, where moisture condensation is a constant concern. The 33x35mm compact form factor of the PT8T allows it to fit into tight rack configurations, while the robust sealing ensures long-term reliability even in 90%+ humidity conditions.

The IP66 rating also means both tubes can be easily cleaned by spraying, an important maintenance consideration in commercial plant factories where hygiene protocols must be strictly maintained between crop cycles.

Spectrum Options

The RX-PT8T offers three distinct spectrum variants, each optimized for different growing stages and crop types:

The F4K spectrum (36W, no lens variant within the PT8T family) is designed specifically for tissue culture and seedling propagation. It delivers 270 μmol/m²/s at 0.15m with a PPF of 90 μmol/s and 6600 lumens, providing gentle yet effective light for young plants.

The F175 spectrum (32W, with lens) is the universal workhorse, suitable for most plant species including vegetables, herbs, and strawberries. It delivers 365 μmol/m²/s at 0.15m and 275 μmol/m²/s at 0.2m, with a PPF of 86 μmol/s. Notably, the F175 consumes 24% less power than the previous generation while maintaining the same light output.

The V3 spectrum (32W, with lens) is the high-efficiency option for rapid vegetative growth. It achieves 2.9 μmol/J efficacy, delivering 416 μmol/m²/s at 0.15m and 316 μmol/m²/s at 0.2m. The V3 spectrum saves 33% energy compared to the previous generation, making it the most cost-effective choice for commercial operations running lights 16-18 hours per day.

Lettuce growing under Koray PT8 tube lights

Daisy-Chaining and System Design

Both models support daisy-chaining, but the PT8T can connect up to 10 tubes in series on a single power feed. With the centralized power supply version, this extends to 20 tubes, dramatically simplifying wiring in large-scale installations. This is particularly valuable in vertical farming setups where minimizing cable clutter improves airflow and maintenance access.

For a standard 1.2m x 1.2m growing area, Koray recommends installing 6 PT8T tubes at 0.3m height to achieve an average PPFD of 300 μmol/m²/s across the entire canopy. The total power consumption for this configuration is approximately 133W per square meter, which is highly efficient compared to traditional fluorescent tube setups that consume nearly double the electricity for equivalent light levels.

Which Should You Choose?

Choose the RX-PT8 if you are on a tight budget, growing only low-light crops like microgreens or lettuce seedlings, or retrofitting an existing fixture where maximum PPFD is not critical.

Choose the RX-PT8T if you need higher PPFD for fruiting crops like tomatoes and peppers, require the flexibility of multiple spectrum options, want to minimize the number of tubes per shelf, or are building a new commercial installation where energy efficiency directly impacts operating costs. The PT8T’s Koray secondary optical technology ensures no center hotspot, meaning plants receive uniform light across the entire growing area without risk of light burn at close distances.

Koray Lighting has been manufacturing horticultural lighting since 2009, with over 200 patents and products exported to more than 60 countries. The PT8T series represents the culmination of over 15 years of optical engineering expertise, trusted by commercial growers worldwide for reliable, high-performance plant lighting.