Coral temperatures

[gman0526]

This thread leads to a discussion on RC about the temp effects of MH lights on corals that are at under less than 6" from the surface of the tank directly under MH light. This corals could be up to 10 degrees warmer than the water column. Anybody care to comment? The study was made by Dana Riddle and was a chance discovery.

http://reefcentral.com/forums/showthread.php?s=&threadid=720214

 

[wrightme43]

It is interesting. I dont want to stick my large foot in my mouth. LOL
I dont understand it. Common sense tells me that cant be, but then again common sense tells me that a pencil lead is solid and cant be mostly open space with a bunch of electrons whiring around inside of it.
I know I can boil water in a paper bag, and it cant get any hotter than 212 untill all the water is gone. I know it takes massive amounts of energy to heat water, and that anything you put in water will quickly equalize temps with it. Light energy transfer thru Air and Light energy transfer through water are not the same if I understand it.
I think that IR can go almost uninpeded thru air but is rapidly absorbed by water.

 

[NaH2O]

Wow that is very interesting! I am curious to what Dana's answer will be to the question you posted. The first thing I thought of was a flow issue, but it seems the Carlson surge device is providing necessary flow. A question I have, do captive corals adapt to the higher internal temperature? I think about tank pics I've seen where corals are growing almost out of the top of the tank. I would also be interested in the coral temperature as the lights come on, and how long it takes to "heat up" and return to the starting temp after lights off (I believe someone else posted that in the thread).

 

[gman0526]

Can anybody see a correlation between this and the fact that some of us are getting great results with shorter MH photoperiods?

 

[NaH2O]

What type of results are you referring to? Coloration, growth, health? I actually hadn't heard that before. I will be interested in the coral temperatures in other types like Acros, etc., if that is possible for Dana to test. There has to be some adaptability factors, but I wonder if these elevated coral temperatures lead to the inability to handle a stressful event. Hmmm...thinking out loud on this one.

 

[gman0526]

I've noticed a trend, at least on RC's SPS forum, of some hobbyists advocating shorter photoperiods specially on BB setups, some even 2 hrs MH because they notice that their corals repond better to this setup. If dana's study is correct and certain SPS do in fact get hotter due to MH exposure for extended periods of time then both topics should be related. I for one have shortened my MH Photoperiod to 4 hrs and the corals seem to responding very good. Nobody to my knowledge has made a connection between both, I'm really just throwing the question out there to complicate the discussion even more .

 

[MikeS]

I've noticed a trend, at least on RC's SPS forum, of some hobbyists advocating shorter photoperiods specially on BB setups, some even 2 hrs MH because they notice that their corals repond better to this setup. If dana's study is correct and certain SPS do in fact get hotter due to MH exposure for extended periods of time then both topics should be related. I for one have shortened my MH Photoperiod to 4 hrs and the corals seem to responding very good. Nobody to my knowledge has made a connection between both, I'm really just throwing the question out there to complicate the discussion even more .

I agree with your question to Dana....kinda like a hot sidewalk soaking up sunlight...that would be my first guess

One of the posts on that thread brought up exactly what I was thinking also....is this any different than what you'd see in the wild? I mean even the best light setups can't be producing nearly the same lux that the wild reef is exposed to from direct natural sunlight....it would be interesting to see what the results were compared to corals in the wild...

another question I'd have would be if this same effect is observed in soft corals that don't have a calcium skeleton...

MikeS

 

[NaH2O]

Mike - Dana addressed the question about wild corals. He made it sound to me like corals in reef aquaria heat up to a greater extent than in the wild.

Aloha Roger,

It is my understanding that preferential heat absorption does occur in natural reef settings, though perhaps not to the extent that I saw in captive corals. However, I did not see it when two thermistors were placed in convenient holes in Porites corals in a tide pool here on the Kona coast.

In aquaria, this absorption occurs only under certain circumstances - corals near high wattage metal halides in an efficient pendent luminaire. Probably happens on a fairly regular basis... What I don't know in this case is how skeletal density might affect heat absorption. Porites corallums, obviously, are porous. What of the dense corals, such as Pocillopora? No answer at this point, at least that I'm aware of.

Dana

 

[MikeS]

Thanks Nikki ...I admittedly skimmed through it pretty quick, I must have missed that....

interesting however that it would be greater in the tank, I'd think the lumin exposure is nowhere near what a coral would see in the wild....interesting

Mikes

 

[plack]

gman0526 so do you use any vho or pc and if so how long are they on for ?

 

[gman0526]

I use 1 t5 32w actinic bulb and 2 175w MH 15 K's. I'm in no way advocating/telling anybody to go ahead and drop their photoperiod, I'm just sharing my experience so far with my tank .

What really made me go to a shorter photoperiod was the fact that I noticed that during the MH light cycle i could see my corals look their best for a period of time of roughly 5 hrs starting at the beginning of the MH photoperiod on. B4 i used to have a MH photoperiod of 8hrs. BTW temp was never an issue since the tank never went warmer than 82.5 degrees.

 

[kahunakatz]

Kahuna Light = Kahuna Heat

That is really interesting because at Kahuna Corals I noticed a huge discrepency between the health of corals and the intensity of light. The tanks are shallow, the corals are on racks, and the reflectors are diamond lumenarcs. The corals that were lit by 400W halides could only have the lights on 4-5 hours a day, while the corals lit by 250Ws could handle 8+ hours, no problem. I think that there is more to it than just heat, but I think that heat is a big deal. When I got a chiller on the system it also made a huge positive difference. I hope that this helps.

Much Thanks,
Barry

 

[MikeS]

I wonder if it also could have something to do with the fact that the MH's are fixed, where the sunlight isn't always in the same place or angle....

MikeS

 

[NaH2O]

I would like to see the results of different coral species, like Acros, montis, etc. before I make any final judgments on what Dana found. I would also like to see different species tested in the wild instead of only Porites.

 

[cwrenge]

That is really interesting because at Kahuna Corals I noticed a huge discrepency between the health of corals and the intensity of light. The tanks are shallow, the corals are on racks, and the reflectors are diamond lumenarcs. The corals that were lit by 400W halides could only have the lights on 4-5 hours a day, while the corals lit by 250Ws could handle 8+ hours, no problem. I think that there is more to it than just heat, but I think that heat is a big deal. When I got a chiller on the system it also made a huge positive difference. I hope that this helps.

Much Thanks,
Barry

Barry.... you mention that when you got a chiller , it made a difference.....? what was the Dif in your tank...? i tend to think that there was a problem with a Temp being steady in your tank....? was there a flucuation of the tanks temp. ? and where ( at what level ? ) are your corals located at in the tank...? i'm just trying to understand your observation of the intensity of light.... was there more than one tank where you observed the changes..... ? cw.

 

[reefer4eva]

i have a question regarding my toadstool mushrooms,i had them for over a month and the polps dont seem to open up.i tried placing them in different positions in the tank and still nothing,all the chemistry is perfect
the tank has been set up for over 2 years everything else is fine and spreading .my tank is a 90 gallon with about over a hundred and 30 or more pounds of live rock ,in my refugium i have plenty of macro algae aswell as mongroves,my lighting is a coralife powercompact 260 watt.not sure if you need more info about the tank?if so let me know.
anyone please help???

 

[NaH2O]

reefer4eva - Welcome to Reef Frontiers!!! I wanted to post a link to your question you posted in Anthony's forum for others to add comments if they wish: Toadstools won't open their polyps