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So for the weekend, I wanted to showcase my reef system to friends coming over for a BBQ. Everyone loves blue hued water, especially our non-reefer friends. Contrary to popular belief, yes, even I do (as I am a notorious 10K bulb user). Without any thought, I made the switch to 20K bulbs on Friday after the lights went out.
Saturday morning, the fish and corals looked brilliant. It reminded me how I loved seeing my corals in a different, more enhanced light. The 20K bulbs burned so blue, that every accent on the corals was pronounced. Reds were blood red, blues were deep blue, greens neon green, and on. It was reeftastic!
Saturday passed on with fish and corals getting the long blue hue treatment. Sunday came with a lot of work ahead. Cleaning the house was in order, so the tanks were given very little attention. The BBQ was cleaned, house vacuumed, and fish were left unfed! Hungry fish always prove to be a great party trick for later on.
Unfortunately, most of my friends love fish, don’t care at all for the corals. Strange, as some of the corals have a lot more personality than some fish. Party trick number two: show people how coral polyps retract into their coral bodies. It gets a lot of “Oooh”s and “Woaaah”s. Works every time. So now, friends are gone, ate my food and were off of my driveway. Now what?
I tend to finish my nights with glancing at graphs and parameters of my system. If you didn’t already know, and have been hiding under a bus (hide-and-seek game was over long time ago), the Reef Keeper Elite controls my entire system and gives me detailed information on how everything is doing. Last night, something was amiss. I was looking at why my pH was looking very low. It was reading at 7.79, a figure that I haven’t seen so far. In fact, it was low for both Saturday and Sunday. On average, the pH runs between 7.85 (morning) to 8.05 (afternoon). So why did I see this anomaly? See the graph.
Resting before going to sleep, I was thinking about what could have caused the pH to drop. Then it hit me… like somebody dropping a 5 gallon saltwater bucket onto my head!
Lack of photosynthesis!
I remember Randy Holmes-Farley stating once long time ago:
Photosynthesis is the process whereby organisms convert carbon dioxide and water to carbohydrate and oxygen.
6CO2 + 6H2O + light à C6H12O6 (carbohydrate) + 6O2
A lower intense bulb, such as a 20,000 Kelvin bulb, will prohibit higher rates of photosynthesis in corals. Conversely, a 10K bulb will have higher intensity, and thus, higher rates of photosynthesis. Hmmm. Another thing that I considered was an increase of CO2 in the basement due to having people over, but that would mean that only on Sunday the pH was low and not on Saturday. So it had to be photosynthesis.
Lower rates of CO2 consumption in the water by corals through photosynthesis caused the pH to stay on the lower side. Having everything else equal (for the most part, aside from having people over on Sunday for a few hours), the difference between 20K and 10K bulbs is the change in rates of production of carbohydrates (energy), CO2 consumption, and production of oxygen.
For me, changing bulbs to 20K was a swing of 0.06 on the pH scale. Note to self, use 20K lights only for a few hours, not days! Thats what actinics are for, right? See ya tomorrow reefnecks!
Trained by the thirteenth ring master of the Sian Xiuang Coral Temple. Currently is apprenticing the art of Acropora shaping in the ancient tradition of Ninja Fragging. Known as the SPS hero!
Hmmm, that’s odd. I run 20K MH and blue T5. PH drops over night to 7.99 and peaks at 8.25 by late afternoon. I would be interested in your PH if you swapped your 10Ks back in.
Mike, but I did. Did you see the graph?
You are probably adding a lot of alkalinity to your tank, or you have 400w bulbs. How many bulbs to you have and how far are they from the water?
another great article … of something that if we thought about it can easily understand. The real value is that there is a number that we can throw around 0.06, good to know.
S
Thats interesting. Dana Riddle wrote something not to long ago that showed the corals have a faster growth rate with 20k http://www.advancedaquarist.com/2008/12/aafeature1/view?searchterm=None
Awesome observations
You should publish an article on this finding and of course, more experiments first.
Chris, in my opinin, that article has great intentions, but has many flaws.
The first flaw that I saw immediately was they didn’t even mention which ballasts were driving these bulbs. And secondly, why use different manufacturers all across the board? They should have used all Ushio bulbs, or all XM bulbs.
In research, constants are your friends, variables are your enemies. They didn’t have many constants.
Like I said, great idea, but bad setup.