During the course of history men have always searched for the unobtainable. The knights of King Arthur searched for the Holy Grail, Captain Ahab obsessed about a white whale, in similar fashion we hobbyists have been searching for how to optimize the coloration in our sps corals and especially Acroporas, since the hobby started.
For the most part I am pretty happy with the coloration of my corals, like everyone else I also want to make sure that I am doing everything I can to maximize their coloration, after all the wonderful colors of our corals is what now makes so many of them expensive. While I was putting together this piece I decided to get the recommendations and thoughts from some of my friends who I think have really great colored corals. So I asked Jason Fox, Sanjay Joshi, Mike Biggar, Cruz Arias and Julian Hechavarria of Elegant Corals, Ben VanderNoort and Brett Harris of Cherry Corals for their input.
This article is not a scientific treatise explaining how one specific fluorescing pigment or a specific clade of Zooxanthellae affects the colors in our sps corals, but rather it is my attempt to find the consensus among these successful hobbyists as to what we can do to maximize the colors in our sps corals. While I am primarily focusing on how to maximize the coloration in sps corals, specifically Acropora, here, following what is discussed will also help get the best colors and health from your other corals as well.
The first thing they all agree on is start off with brightly colored corals. Luckily unlike the early days of the hobby when most of the sps corals were brown, now most of the corals we see are brightly colored from the start. This is especially true of the countless “designer” frags that are now available. Please note when I am discussing optimizing the colors in our corals I don’t mean to get them to the point where they look like the photoshopped, over-saturated corals that we see from some vendors online, but rather to bring out the true colors of these corals, which to my eyes are still quite incredible.
Once you have acquired colored corals you want, the next step is to light them properly. This used to mean blasting them with as strong a light as possible for as long as possible. Fortunately with the advent of LED lights and more efficient metal halides and t-5 bulbs we have found that replicating the sun is no longer necessary to get the best colors out of your corals.
Unlike the other choices in lighting LEDs focus the majority of the light they produce down directly on to the corals. So while a tank lighted with LEDs may look less bright than one lit with metal halides, the reality may be that the corals are actually getting more light focused on them. As a result, corals need to be acclimated slowly to this type of lighting. These lights are so efficient that rarely is it necessary to run them at full power. The general consensus is that a PAR of 450-650 umol is good to maximize the color for most of our sps.
In my own experiment this summer where I set up a tank so that it would receive direct sunlight for 4-6 hours per day, during this time the light PAR on the tank reached over 1250 umol. Even though this lighting duration was for a shorter period of time than we run most lights on our tanks the Acropora in this tank initially turned brown after a couple of weeks in this light and then eventually bleached out. So even though this is Pennsylvania, the intensity of the light was too much due to the shallowness of the tank. I should point out that during the phase when the Acroporas were turning brown, the corals looked very much like the corals I’ve seen on the reefs with there being very little color on them other than brown.
But intensity is just part of the equation for optimizing color. The spectrum of the light also plays a significant role. While tanks that are predominantly lighted with blue lights will bring out a lot of color in the corals it will tend to wash out the pinks and light purples in the corals and most yellow corals will turn green under this type of lighting.
As a result in order to see the full spectrum of coloration in corals a full spectrum of light is suggested with it looking blue/white rather than completely blue. This lighting may include UV and infrared, but there was no consensus as to how much this helped in coloration. Pure blue light was suggested to be used at the beginning and end of the day to maximize the colors and to get that “pop” on the corals that many of us like.
After lighting the next aspect for maximizing coloration was water quality, with stability being the aspect that everyone agreed on. I will discuss what everyone feels are stable water parameters in a more in depth future article, but needless to say, no one felt having things fluctuate wildly in a tank during short periods was good for the corals. Chief among the parameters that should be stable was alkalinity. There is little consensus as to what the optimal alkalinity should be. However there was an interesting relationship between nutrient levels and what people thought the alkalinity levels should be.
When people kept few fish and hence had low nutrient levels, low to almost zero levels for nitrate and phosphate they preferred lower alkalinity levels of 7.5-9, while if they kept lots of fish and had higher nutrient levels, NO3 at .05 and higher and PO3 at .03 and higher they tended to recommend alkalinity levels of 10-12. However no one recommended that NO3 and PO4 be at 0 as they all have seen that coloration and the health of the corals suffers when no nutrients are present for the corals to consume.
In addition to maintaining stable water conditions as well as some nutrients everyone agreed on the need for some trace element additions either directly or via water changes. Some of the additions that were suggested were specific to bring out specific colors: iron for greens, potassium and manganese for reds and pinks, and potassium iodide for blues and purples. These elements work in a variety of ways and effect the pigmentation of the corals directly and indirectly.
If your corals seem to be lacking or losing these colors over time the addition of these elements can be gradually increased over time. The one other thing that everyone stressed in doing everything in their tanks was to make any changes slowly, once again stressing that any instability or rapid change is bad for coloration.
Just adding these elements was not thought to be enough though to maximize color, it was also felt that providing for the nutritional needs of the corals also greatly enhanced their coloration. In this regard providing a wide variety of foods specifically for the corals was thought to be beneficial as was the addition of amino acids. Some also thought that adding phytoplankton may provide additional benefit in keeping the food chain alive in the tank, but this was not everyone’s opinion.
The other aspect that everyone agreed on that was important to maximize coloration was adequate flow. Unfortunately “adequate flow” is a somewhat subjective terms. What may be good flow for one coral may sheer off the tissue for another so it takes time to get the right level and type of water motion for each tank and it does change as the corals grow. The main benefit of good flow is it allows the corals to slough off excess slime. Proper flow allows the corals to not only eliminate waste but also to free it from any pests that have adhered to the slime as well as for the corals to more readily take in trace elements and other important compounds and nutrition.
Lastly everyone agreed that one of the most crucial aspects to maximizing the coloration in our corals is giving them time to settle in and time to grow. The consensus was that any time a coral is manipulated or its tanks conditions changed significantly it takes at least a couple of months for it to resettle in and thrive. Therefore once you have tweaked the conditions in your tank to promote good growth and coloration in your corals you need to give them time to thrive in this environment.
Constantly tweaking the conditions or moving the corals about is not going to get you the coloration you want. A reef tank is the ultimate work in progress and we are seemingly always waiting for one coral or another to “color up”. Sadly some corals will never show the same coloration that we see in a picture online, but even at their worst, most corals when taken care of properly and where the above suggestions are followed will be far more colorful than just about any other living thing we can keep and maintain for the long term.
I realize that many of you probably have additional thoughts and ideas on how to maximize coloration, and I appreciate your input in the comments below. I would like to thank my friends for taking the time to share with me what they are doing to have such colorful corals.