Osram Vialox NAV-T HPS Lamp – SON-T Grow Light Bulb
Osram Vialox NAV-T HPS Lamp – SON-T Grow Light Bulb
In stock
Couldn't load pickup availability
Share
Order by 3pm Mon–Fri — we aim to post same day · FREE Express Delivery over £99 · 1–2 working days · Free Wembley pickup
- 14-day returns
- Price match promise
- Free Wembley store pickup
- Advice from the team: 020 3488 0419
Description
High-Output Sodium Light for Strong Flowering and Fruiting
The Osram Vialox NAV-T HPS Lamp is Osram's clear tubular high-pressure sodium lamp, giving a warm, red-rich light of around 2000K – the part of the spectrum that drives flowering and fruiting – on a standard E40 cap that fits any E40 HPS lamp holder. The 400W and 600W lamps are Osram's higher-output NAV-T SUPER 4Y, sold on the box as SON-T PLUS: Osram rate them at 56,500 and 90,000 lumens (up to 150 lm/W) with a 32,000-hour life. The 1000W is Osram's standard VIALOX NAV-T (SON-T), rated at 130,000 lumens. Choose the wattage that matches your ballast.
Key Benefits
- SON-T PLUS output at 400W and 600W – the higher-output Super 4Y version of Osram's Vialox sodium lamp
- Up to 150 lm/W on the 600W for strong canopy intensity from every watt
- Red-rich 2000K spectrum suited to flowering and fruiting crops
- 4Y long-life rating on the 400W and 600W – Osram rate them at 32,000 hours, still giving 94% of their light at 12,000 hours
- Standard E40 cap – fits common HPS reflectors and lamp holders
- Three wattages – 400W, 600W and 1000W to match the ballast you run
Why Is My Flowering Weaker Than It Used to Be?
Most HPS lamps never actually blow; they simply lose output month by month. The decline is gradual and easy to miss, but plants notice it: slower growth, excessive stretch as they reach for light, and lighter flowering and smaller fruit in a room where the feed and climate have not changed. Relamping with a high-output sodium lamp brings light intensity at the canopy back to where it should be, and running it on a ballast of the same wattage means it delivers its full rated output.
How to Use
- Match the wattage: run the 400W lamp on a 400W ballast, the 600W on a 600W ballast and the 1000W on a 1000W ballast – magnetic or digital
- Cool down first: switch off and let the old lamp cool fully before you remove it
- Keep the glass clean: hold the lamp by its cap or wear clean gloves, then screw it firmly into the E40 holder
- Set the height: start higher over young plants and lower gradually, using a PAR meter or the leaves as your guide
- Relamp on a schedule: most growers replace HPS lamps every 9 to 12 months of grow-room use, before output has visibly faded
Technical Specifications
- Brand: Osram (Vialox range)
- Model: VIALOX NAV-T SUPER 4Y (SON-T PLUS) at 400W and 600W; VIALOX NAV-T (SON-T) at 1000W
- Type: high-pressure sodium (HPS), clear tubular
- Wattages: 400W, 600W, 1000W
- Cap: E40
- Colour temperature: approx. 2000K
- Light output (Osram): 56,500 lm (400W), 90,000 lm (600W), 130,000 lm (1000W)
- Efficacy (Osram): 141 lm/W (400W), 150 lm/W (600W)
- Rated life (Osram): 32,000 hours (400W and 600W Super 4Y), 20,000 hours (1000W)
- Ballast: standard magnetic or digital HPS ballast of the same wattage
- Lamp size (Osram): 28.5 cm long x 4.7 cm diameter (400W and 600W); 36 cm long x 6.6 cm diameter (1000W)
- Best stage: flowering and fruiting
Frequently Asked Questions
Will it fit my reflector and ballast?
The E40 cap fits any standard E40 HPS reflector or lamp holder. Run it on a ballast rated for the same wattage; on a dimmable digital ballast, set the ballast to the lamp's wattage. The 1000W lamp is longer and wider, at 36 cm, so use a reflector made for 1000W lamps.
Is the NAV-T Super the same as SON-T Plus?
Yes. Osram print '(SON-T PLUS)' on the Super 4Y box – it is the higher-output, longer-life version of their standard Vialox NAV-T. The 400W and 600W here are the Super 4Y; the 1000W is the standard NAV-T (SON-T).
Which wattage do I need?
The one your ballast is built for: a 400W lamp on a 400W ballast, 600W on 600W and 1000W on 1000W. A bigger lamp lights a bigger area, but it also needs more height above the plants and stronger extraction to carry the extra heat away.
Can I use it for vegetative growth?
It will grow plants through every stage, but its red-rich 2000K light is at its best in flowering and fruiting; many growers use a metal halide or LED for vegetative growth.
Works Well With

FREE Express Delivery on orders over £99. We aim to post same day on Express Delivery — order by 3pm Mon–Fri — and delivery takes 1–2 working days. A few harder-to-stock or large, bulky items can take a little longer — we'll tell you if that applies to your order. Heavy-item surcharges are always shown at checkout before you pay — we only ever charge what delivery costs us. Prefer to collect? Free pickup at our Wembley store.



