too much light

[jimmy911]

is there any chance you could have too much light.....

i reacntly upgraded too 2 250 mh`s and my nems seem to have run for cover and toad stools closed up my tank in 24" deep and ive always read 150w per foot is perfect but would love your opinions

many thanks tony

[simon garratt]

Hi tony,

the general concesous among experts is that its a 'no' in most cases with the current technology we have. In the wild, upper reef-slope and reef flat animals are subjected to levels in exess of 1000w/sqm for good portions of the day. Admitedly, this isnt an ideal guage (watts) becouse it doesnt tell you much about the nature of that light, but for aquarist using any of the most common lamp/reflector combinations available its not a bad measure and pretty easy to understand or imagine. when we start talking lumens and par etc, most go glassy eyed or get totally confused. so watts is the most common means of expression when we talk about how much light our corals are getting.

whats more of a concern to most animals is how they are subjected to that light, both initially and over the long term.

In general when switching over to high power lighting or when a coral etc is rehoused /imported from a dark shipping bag/ occasionally dully lit dealers tank. Its very good practice to place the coral as low down in the tank for severaldays, and then gradually raise it up. Or if switching lights, to both have them raised up initially to spread the intensity out over a larger area, or to reduce lighting times by several hours. both of these practices require a few weeks of adjustment back to noprmal so the animals can build up protective pigments again that they may have previously lost, or never had to start off with.

Im hazarding a guess that your anemone sufferd whats commonly called light shock. Effectively its been over illuminated and has retreated from the higher intensity for a short period whilst it adapts. (commonly taking several weeks to slowly and increasingly expose itself to the full glare of your new lights.

I shouldnt worry too much at this stage (just let the anemone do as it wishes and hope everything is going ok for you.


My appologies for the late response as this one slipped my attention.

Regards

Si.