Discussion in 'General SPS Discussion' started by madweazl, Dec 29, 2017.
Before LEDs, did we have this conversation?
I haven't been a member of forums long but a quick search suggests the die off at the base of acroporas has been happening long before the introduction of LEDs.
I do not think you are crazy.
I do think there is an explanation.
There's also a parallel with land plants.
When nutrients are insufficient, they will take nutrients from more shaded older lower branches/leaves in order to grow the top of the organism.
So in my opinion at least it is a side effect of starvation.
@madweazl I think the dual "pop trends" of low nutrients and ultra-wide (i.e. soft!!!) flow are also feeding into this phenomena along with lighting....all related to nutrition.
When questions like these arise, I like to look to the wild for answers. These corals are considered reef building corals, so without some eventual die off, how can the corals contribute to the growth of the reef/ provide room for new coral growth. I found this image online of a large staghorn acropora. You can clearly see the underside is pale as well as the base, but is it receding?
Granted, this is a very mature colony. Nothing we have is anywhere near as mature.
My hypothesis is that flow is a larger contributor to die off than lack of light. If the polyps can eat, that provides nourishment to the surrounding area. Without flow/particulates, the shaded areas die because they are acting as NPS portions of the coral due to the loss of pigmentation. Granted, I can see that a coral used to growing only in well lit conditions may have trouble adapting to low light/ shaded conditions.
Something else I forgot, flow also keeps detritus from settling, but I imagine it can't stop it completely. This is where the many different animals that call branching corals their home come into play. They perform their own house keeping on a large coral to keep it healthy. We lack all/most of these animals in our aquariums.
Agree 100%. You can tell it isn’t the flow when you can see a crisp line on the coral perfectly corresponding with a crisp shadow, like you’re holding your hand just above the sidewalk on a sunny day. I’m not talking about general sps base recession.
MH were the old standard of “point source”, but actually half of their light is directed up into the reflector and spread out over a ~24” area. New style point source LEDs are much more “point source” then MH.
I am going to increase flow on mine to see if it helps, my coral all grow well but once they start having multiple branches I started noticing the shading.
Something else is that these corals (brancing, primarily) are self-shading by their own design. And as I mentioned, light is only part of the nutrition equation. Light = food. Flow = food. Paricles/detritus = food. They moderate all three resources to maintain themselves. So you can't really blame just light, or just flow, etc. It's starvation-related.
To say it another way...
If shade makes your corals tissue recede, then:
you know there was not enough flow
and/or dissolved nutrients
and/or particulate food to make up for it.
To blame shading alone seems silly...even if it seems apparent. Corals are better survivalists than that.
While I agree the organism is too complex for one single explanation, I have mega flow with this problem. The coral is large, healthy, colorful, and growing well. Only the area with no light, the underside, experiences die off. Further evidence, I've hacked off large chunks and previously dead areas are grown back over. I have the opposite of ULNS as well. I feel confident in my case, die off is directly attributable to lack of light.
@McMullen Any chance you have some pics so we can see what you're referring to?
Where do you keep you N and P numbers, or where do they typically fall?
What do you use for flow and how large is your tank?
How about what you use for filtration or filter media?
Last, what do you feed the tank and how often?
Not doubting, but these are all interesting questions if things really are as they appear to you.
Video wouldn't upload, wanted to show this area gets a ton of flow.
I dont test N and P
No skimmer(recent change as I was only changing collection cup monthly)
Run carbon, but only change every couple months
Feed heavily, chunks of raw shrimp, mysis, and pellet.
Jebao 8w and PP 20 and Sicce (idk model but think it does something like 3000gph)
Tank is 140gallon (same footprint as 120gal but 30in tall.
4 black box LEDs ( just switches to only three) hung 19in from water.
Those are real, substantial colonies where you start to see problems.
Do people discount the really solid hobbyists with a wide enough breath and depth of experience to know the difference and how to run a tank that unequivocally experience this only with LEDs and have since added T5s or gone back to what they had before? Anybody can find a post about anything, but when decade-long excellent hobbyists post about shadows of LED light being a problem (Joshi, Plaetta, etc.) ,we ignore that and choose what we want to choose and blame other things like flow? These folks know how to adequately flow their corals. There is an actual common denominator here and it is not all that hard to see.
Do you have examples? Did Sanjay add T5s (he was using Radions exclusively until recently if so)? He also stated he had no doubts LEDs would be fine when he made the switch. I know Mike Paletta wasn't thrilled with LEDs from a 2013 article but I'm not sure what his thoughts are now.
He replaced each MH with 3.33 Radions to help with the shading, yet still has issues. Did you forget, or just not know, that he lost all kinds of colonies when he first switched - lots of large, dense stuff and all of the Millepora. He indicated in his MACNA 2015 talk that he knew that this was an issue from day one and started with eight, but now has ten units. He has been very honest and open about his experiences yet people still seem to only see what they want to see: he will flat out tell you that there is no power savings and also that they do not cover as well and you need a lot of units to avoid some shadows (but he still has them).
There are examples on this thread, and you have seen some that you mentioned in your original post. It might be smart to not discount them and have a plan... rebuilding colonies once they start to go is not easy and you sometimes feel like you wasted all that time growing them in the first place. One day, folks discount the issue and then soon after they have corals that look like those in post #51.
I am only trying to help. If your thread title is a statement and not a question, then I will bow out since I don't believe it to be true and have nothing to further the conversation of shading being empirically BS.
I'm aware he had a crash due to a chiller failure that prompted the switch to LEDs (to lower heat levels, not power consumption as he replaced 1200 watts of MH with 1200 watts of LED). In regard to the amount of fixtures he's running, the tank is 7x4x2.5; I don't find 10 fixtures to be absurd when you're talking about a tank of those dimensions. He does state, "with the coral grown in I began running out of space and wanted to get more light in the corners..." in this interview.
I have shading with 5 Kessils on my 92g, but its only in areas that are well overgrown with corals. I dont think a t5 or mh would lite those areas either.
Can you please quote any or all of the individuals you were citing please?
If possible I'd like to see these conclusions in their words, with any available context.
The original question is less about the type of emitter and more about shading itself. In this thread, we've seen some frags in a shaded area that seem to be dying off that have what appears to be substantially more light than one of my own (hard to tell from an image). Two very different results from even frags on what otherwise appear to be healthy corals; doesn't that suggest there has to be at the very least, a combination of causal factors?
I think @mcarroll is likely right in that starvation is the cause of die off but this begs the question, just how much nutrition can a coral uptake from the water column without adequate light? Anemones that have completely bleached are capable of surviving if fed directly and can return to a normal state of being once provided adequate lighting again. Can an acropora do the same?
A previous statement about the die off contributing to the building of the reef structure was another interesting point. Is there an innate response from the coral to do such?
@madweazl, I suspect confirmation bias is at play here.
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