# Understanding LUX readings - what is ideal?



## dapellegrini (Jan 18, 2007)

Does anyone have a good link on LUX/PAR measurements in the planted tank? I am wondering what ideal ranges are.

I just got one of these SM700 LUX meters in a bid to quantify just how much my T5's diminish over time. This coincides with needing to change out the T5's in my Tek 24" after 12 months - they are just WAY too dim. So here is what I have so far:

Tek 4x 24w T5 over ADA 60-P; 2x Giesemann Midday 6k and 2x AM Planta 6k:
- After 12 months LUX reads 5,500 from bottom of tank in a bright spot
- New bulbs (not exactly the same: 2x Sylvania GroLux 6700k and 2x AM 10k) read 9,500 from same spot

Tek 4x 54w T5 over ADA 120-P: 2x Giesemann Midday 6k and 2x AM Planta 6k:
- After 4 months lux reads about 9,000 from bottom of tank in a bright spot

I wonder how all of this stacks up...


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## dapellegrini (Jan 18, 2007)

Well, I read somewhere that plants will continue to suck up light to about 20,000 LUX after which point it becomes counter productive to add more. Algae can apparently use light up to about 35k LUX.

I still haven't figured what ideal ranges are for plants, or where I should be measuring the light from.

At the water surface I get between 44,000 and 46,000 LUX - amazing how much less actually makes it through to the bottom of my tanks in comparison...


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