Changing The Color Temperature Of Lights

[Mr Bliss]

My old 10,000 K metal halide is coming to the end of its recommended lifespan, and I've been thinking about switching to a warmer light, somewhere in the 4000 - 6500 K range, because 10,000 K makes everything look slightly unnatural to my eye. Granted, the blue shades of emperor tetras and blue gouramis practically glow, but reddish plants don't look as good as they should (for example, I can only tell that my Ludwigia glandulosa is actually red after I trim it and take the cuttings out of the tank).

Has anyone has any bad experiences with such sudden changes in light temperature (wattage remains the same, although the new bulb will be brighter by virtue of being new). I reckon it might take a while for plants to optimize their physiology to the new light, but will this mean just slower growth for a while, or should I expect something worse? Dying leaves? Algae blooms? Some plants failing to adapt? I'm particularly worried about algae, because I don't want to resort to dosing Excel as I have plenty of Vallisneria in the tank, and I've just recently won a two month battle against BBA after some summertime neglect.

If its relevant, my plants are Echinodorus bleheri, Vallisneria spiralis, Microsorun pteropus, Pogostemon helferi, Ludwigia glandulosa, Hygrophila difformis, and some small unknown Echinodorus that's too big and broad leaved to be tenellus.

 

[aaronnorth]

A change in colour temperature could stall growth for 1 or 2 days while the plants adapt chlorophyll pigments
The higher intensity would more likley cause an algae bloom for obvious reasons, but once the growth is back to normal then everything will be fine.

Overall, you shouldnt notice a difference.

 

[Jallen]

I've found that higher temperatures seem to cause brown algae strangely.