Can VHO's make coral colors shift?

[Brad Villeggiante]

I currently run 1x10K 250 watt Ushio MH bulb supplemented with 2 96 watt actinic VHO's and 2 96 watt 10K VHO's. This, I have decided, is just too yellow for me. I like the growth of the 10K and therefore want to try to knock out the yellow look by swapping around my VHO's. I was thinking of going 3 actinic VHO's and 1 12K VHO.

Obviously this will make my tank have more of a blue look which is what I am going for (but not too blue, I want something maybe around a 14K aquaconnect bulb look). My question is, with this more blue look could some of my corals colors change (the actual coral change color not just the lighting making it look different) or does coral color change require changing the MH bulb?

[invincible569]

Yes it would. Actinics spike at 420nm and 10k's do not. It would definitely improve the color. Adding Actinics to 1ok's is a must. I have that myself and couldnt live without actinics. The balance is perfect washing out the yellow.

[mesocosm]

Greetings All !

... or does coral color change require changing the MH bulb?

No, the shifting of lighting system spectra in order to influence coral pigment production is not MH dependent. Alteration of VHO light sources can produce meaningful changes in coral pigment production. From a purely aesthetic perspective, I like the kind of balance you're talking about creating ... retaining growth (... and really cool moire patterns ...) with a powerful 250W 10K MH core, while balancing out the visible spectrum by supplementation with VHO actinics. This is a "classic" lighting configuration that should solve any concerns about too much "yellow" appearance, while slowly shifting the pigments produced within the corals. Guys like Albert Thiel were writing about the effectiveness of this configuration back in the early 1980s ...

... and I heartily agree with invincible569's assessment .

Please be reminded that, "Some forms of fluorescent lamps, particularly HO and VHO lamps, produce significant amounts of UV light, necessitating UV shielding for organisms closest to the surface (Delbeek & Sprung, 1994)." Changing out VHO bulbs is not as totally risk free as it might appear, but given that VHOs are already a part of your lighting system, I wouldn't think that you would have any "new" problems.

My question is, with this more blue look could some of my corals colors change (the actual coral change color not just the lighting making it look different) ...

Great question ... many people fail to make the distinction between the color change superficially produced by pigment fluorescence, and a fundamental "real" color change resulting from a shift in pigments within coral tissue.

This "color" stuff is a "thing" with me ... please excuse the rant ... ...

What your asking about is technically referred to as either "photoacclimation", and/or "photoadaptive response." Interestingly, but hardly surprisingly, such responses that place within both the zooxanthellae population and the coral host.

It turns out that corals can respond to changes in lighting by, "... adjusting or changing the following parameters: The amount of pigments in the algae photosynthetic units (PSUs); The size of PSUs; The number of PSUs; The characteristics and number of zooxanthellae; Dark respiration rates; The sensitivity of photosynthetic response; The zooxanthellae respiration rates; Enzyme characteristics; The pigment content of fluorescent reflecting or absorbing proteins; The rate of feeding by prey capture or absorption; Biosynthesis patterns; Polyp expansion; Polyp respiration rate; Polyp density; The production of protective enzymes and pigments (Aquarium Corals, Eric Borneman, 2001)."

If you haven't had a chance to read Borneman's book, you might consider it ... GREAT stuff, IMO.

HTH.

[Brad Villeggiante]

WOW, very good information, thank you both very much. Do you think the lighting configuration I am going to switch to is pretty descent?

[mesocosm]

Greetings All !

Do you think the lighting configuration I am going to switch to is pretty descent?

250W 10K MH + 386W VHO actinic = SWEET!



JMO ... FWIW.