Originally Posted by standoyo

Hi anakcili,

1) Is it true that blue light will make plant become shorter and denser. As for the red plant it will become more red?
False and the opposite for red plants. looks more dull. The CRI[colour rendition index] of blue light makes red plants look blue/purple.

2) If this is correct where to purchase blue light? I notice that Nirox PL tube have 1 white and 1 blue. Does this light really make plant grow shorter, denser and red?
The PL you are talking about are supplemental bulbs for marine tanks that have MH lighting. Meaning a luminaire that includes MH and PL.

3) How long can a PL light last? I was told that PL light need to be change every 3-4months. Is this true?
False.you can use 6 to 18 months. I have what really matters is are you giving the bare minimum at start of your tank.
If you are, then when the efficiency of the bulb drops then your plants cannot grow.
Other reason to change is when colour temp of lighting changes as it ages or getting a bad bulb.

HTH


Regards

Stan