The Lumatek 250 W and 400 W HPS grow light kits contain everything for a high pressure sodium lamp: ballast, Euro reflector and bulb. The 250 W kit covers a 60x60 grow tent, the 400 W an 80x80 and at most a 100x100. For the same area an LED uses about 30–50% less electricity: see the models under LED grow lights.
An HPS lamp cannot be plugged straight into the socket: it needs a ballast that ignites and powers the bulb, a reflector that directs the light onto the plants, and the bulb with an E40 base. In the kit the three parts are already matched by wattage. Choose by tent size:
| Kit | Grow tent | Monthly use on 12/12 | Cost at 0.30 CHF/kWh |
|---|---|---|---|
| Lumatek HPS 250 W | 60x60 cm | 90 kWh | about 27 CHF |
| Lumatek HPS 400 W | 80x80 cm, at most 100x100 cm | 144 kWh | about 43 CHF |
Add a small ballast loss on top. In the vegetative stage, with 18 hours of light, consumption rises by half.
Start at 40–60 cm between lamp and tops (the 250 W can hang a little closer) and check with a thermometer at canopy height: in flowering you want 20–26 °C with lights on. Almost all the electricity becomes heat, much of it radiated onto the tops. So with HPS, size the extractor fan for 1.5–2 air changes per minute instead of one: for an 80x80x180 tent (1.15 m³) that is about 105–140 m³/h, plus a 30–50% margin for filter and ducting.
Prices are in Swiss francs including Swiss VAT. We ship throughout Switzerland with Swiss Post, and bulky parcels go by courier. For help with choosing between HPS and LED, ask the Gro.w.LaB team: contact us by email, call +41 79 359 67 58 or visit the shop in Quartino by appointment.
In a home grow tent, LED: for the same light it uses about 30–50% less electricity and puts less heat on the tops. HPS makes sense if you already own one or grow in a cold room.
On 12/12 about 144 kWh a month (0.4 kW × 12 h × 30 days), about 43 CHF at 0.30 CHF/kWh, plus ballast losses. On 18/6 it is 216 kWh.
An 80x80 cm grow tent, at most 100x100 cm. For a 120x120, the light of a 400 W HPS is not enough in flowering.
About 40–60 cm from the tops. If it gets warmer than 26 °C at canopy height, raise the lamp or increase extraction.
