Sun Tunnel Light for Phalaenopsis: Lux Meter Readings and Supplemental Lighting

You have an east-facing sun tunnel and a lux meter with x1, x10, x100 ranges. Phalaenopsis need 1,000–1,500 foot-candles (10,000–15,000 lux). Your readings are inconsistent across ranges.

Meter Troubleshooting

• Measure incident light: place clean white paper at plant level, point meter at paper (no shadow).
• Readings should scale: x100 ≈ 060, x10 ≈ 600, x1 ≈ 6,000 for 600 fc.
• Your x1=1240, x10=142, x100=015 suggests meter quirks.
• Contact manufacturer (Mastech MS6610) for clarification.

Practical Alternatives

• Hand-shadow test: diffuse shadow at 12" = sufficient for Phalaenopsis.
• If light is marginal, supplement with 4-ft cool-white fluorescent shop light close to leaves.
• Phalaenopsis tolerate down to 600 fc; 30–60 fc is too low.