Corals turning pale

Discussion in 'Coral Health' started by Sacul1573, Jun 14, 2011.

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  1. Sacul1573

    Sacul1573 Millepora

    Dec 1, 2010
    Alk stays at 10, I dose twice weekly to keep it there (not a huge demand yet).

    Temp swings 3-4 degree F, more than i'd like. Stupid return pump is a wattage hog dumping heat in my tank...
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  3. m2434

    m2434 Giant Squid

    Jan 11, 2011
    Some possible reasons for fading (you've covered some, but still maybe they will give you ideas) :

    1) Strong lighting
    I think this is possible, also, maybe they are not being acclimated sufficiently. Acclimation can take a long time if the light sources are significantly different. And different could be with regards to spectrum, not just intensity. Acclimation ideally should be to intensity though, more than duration even. Duration of lighting actually has been shown to have much less of an effect with regards to photodamage than intensity. Using several layers of screen over the tank and removing one every few days, then ramping up the duration is a great way to acclimate.

    2) Insufficient food sources
    Coral can get up to 95% or so, of their food from light. However, light alone can lead to some theoretical issues and has been shown to result in real world problems. I don't know of any evidence to suggest that starved corals will bleach on their own, but are more prone to bleaching as a result of environmental stressors. Starved corals have been experimentally shown to be more prone to bleaching when temperatures rise for example. Zooplankton and bacterioplankton are the main food sources available in our systems, if there is something limiting these in your system, this could potentially be resulting in starved corals. Dosing phytoplankton to encourage zooplankton for example could be beneficial as long as you can keep nutrient levels under control.

    2) Insufficient flow
    Zooxanthellae, in response to light, produces oxygen and other radicals. These build up in the corals tissue and cause damage. Flow helps the coral expel them. Also flow can help prevent sediment.

    3) Temperatures or temperature swings outside of the acclimated or maximum/minimum tolerated range.
    Corals can adapt to a very wide range of temperatures and even temperature swings. Some reefs can have temperatures over 90deg in the summer and others temperature swings as much as 15deg daily, without ill effect. However, if a coral isn't used to a given temperature range, or not physiologically capable of adapting to those conditions it can bleach. So, like lighting, careful acclimation to temperature is required. This is more difficult than lighting, but, the ranges you mentioned should be well within the tolerance ranges of any corals commonly collected, so I doubt this is an issue. You could try to stabilize you temp a bit, but 3 or 4 degrees is really not that much and may be an issue for an occasional coral, but not every coral you put in your tank.

    4) PH - low or high ph should be avoided. Make sure the daily minimum is over 7.8 or so, and the max is 8.4ish or less.

    5) Heavy metals or other toxins.
    This is the toughest one to detect. However, use of a poly filter and aggressive carbon use, with a high quality, low dust carbon can help. Regular water changes can prevent accumulation of toxins. The toxins tend to settle and accumulate in the rocks and sand though. Once there they are difficult to remove and these substrates can act as a sink allowing them to continuously enter the water column. If it gets to this point, replacing the substrate is sometimes the best option.

    6) low nutrients - too low nutrients can starve the zoox. This is uncommon, but can happen. In this case a nitrogen source such as amino acids may help.

    7) Swings in salinity and other water chemistry parameters, or high/low levels of required elements or trace elements.
    Last edited: Jun 14, 2011
    1 person likes this.
  4. Sacul1573

    Sacul1573 Millepora

    Dec 1, 2010
    Great post! Karma to ya!