Lets talk about lighting an SPS tank

[7thheaven]

Thanks Nathan...

I am waiting your reply for a long time.... :-)

How about VHO-on time? Are you down two?

Thanks in advance~!!!

[NuclearReefs]

Sorry 7th,, I didnt see that posting til the guy after you posted,,, Too much email.. I am presently letting my VHO's on at 9:30 am and off at 9:30pm.. its 4 bulbs,, 3 are actinic and one is aqua sun all URI on a icecap 660.

Nathan

[dphins]

NuclearReefs
What time do you run your mh? I would think you would have them on when you are watching the tank and not when you are there?

[NuclearReefs]

they run in the middle of the day ,, I catch them for about a hour or two,Im in the process of moving as well so I trying to seperate myself from thank because Im not looking forward to taking it down to move it ...


Nathan

[Darrell Ward]

Originally posted by my2girls
Flatlander, those are very interesting observations. I don't think SPSers like to here that VHOs keep better SPS corals. They have pride in their halide set-ups. However, I don't doubt you findings for a second.

IMO as long as intensity is there, Kelvin ratings are a personal preference.

IMO flow rate is very under rated.

Water clarity is sometimes overlooked also.

[Julio]

that is why there is another thread regarding water quality.

[JB NY]

Originally posted by Julio
that is why there is another thread regarding water quality.

[ATJ]

Originally posted by Darrell Ward
Water clarity is sometimes overlooked also.

How much difference do you think water clarity makes to lighting?

[Julio]

it makes a tremendous difference, if your water is not clear yoru light penetration will be diminished and the colors on your colras will start to fade.

[ATJ]

Originally posted by Julio
it makes a tremendous difference, if your water is not clear yoru light penetration will be diminished and the colors on your colras will start to fade.

I'm sorry, I wasn't clear with my question. What percentage difference will it make? e.g. How much light from a percentage perspective would be lost between a super clear tank (running Ozone, carbon and/or something similar) versus a standard tank with a little bit of organic yellowing?

Why will the colours fade? What is the physiological reason for "fading" of the colours?

[Aged Salt]

Hi Andrew, fading of coloration can be from nutrients accumulation, resulting in a proportional increase of the zoox. density. A rapid change in water clarity will cause SPS bleaching, especially toward the top corals, ie. beginning carbon in a o/w non-carbon run system, or exchanging too much carbon quantities, beginning 03, etc. I've not noticed this phenomena in LPS but SPS can be adversely affected. Bob

[Aged Salt]

I need moe coffee, the increased clarity also increases photoilluminating color pigments within the coral tissue. Bob

[ATJ]

No-one wants to take on my challenge to guess the impact of water clarity on lighting in an aquarium!

My measurements show that the impact of water clarity on light transmission is not all that high. See: Light transmission in aquarium water: How important is water clarity?. I found that the loss in irradiance from air (and you aren't going to get water that clear) to yellowed old aquarium seawater was less than 20%. The increase in irradiance from the old seawater to air was less than 25%. The actual losses in a tank will be less because even with ozone and carbon you would not have water as clear as air.

A change in irradiance of 25% will cause no more than a 25% change in the gross photosynthetic rate. This is because the curve of photosynthesis versus irradiance is initially a straight line (at low irradiance). As irradiance increases, the rate of change in the photosynthetic rate decreases and so the impact of the change in irradiance could be much less. Such a small change in irradiance is likely to only cause a small change in the density of chlorophyll in the zooxanthellae. This will probably be too small to even be detectable as a change in colour of the coral.

An immediate increase of irradiance of 25% is not going to cause bleaching, unless the coral was already stressed. There have been numerous studies into photoacclimation in corals with increases in irradiance far larger than 25% and the colonies do not usually bleach. In one study, Stylophora pistillata colonies adapted to shade (10% of surface irradiance) were placed in full sunlight (100% of surface irradiance) and there was no bleaching. That's a 900% increase! Further, it would be difficult to cause an immediate increase in water clarity, other than doing a 100% water change and then it would be the water change that would cause the stress and bleaching.

An increase in zooxanthellae density due to elevated nutrients is unrelated to irradiance changes due to water clarity - although the two may coincide. Further, an increase in zooxanthellae would not cause the coral to fade but would make it darker. Certainly, it may become more brown and so appear less colourful, but that is not fading.

The function of coral pigments is not known. It has been suggested that fluorescent (GFP-like) pigments may be photoprotective and there is some evidence to support this. There is also conflicting evidence such as two colonies of the same species side by side receiving the same irradiance and one has GFP-like pigments and the other does not. If you assume that the GFP-like pigments are photoprotective, changes in irradiance may influence the density of the pigments. However, a change in irradiance of 25% is likely to have little impact on the coral and little need for a change in photoprotective pigments.

Pocilloporin (the pink pigment in pocilloporids) and the pocilloporin-like blue found in acroporids has been shown to not be photoprotective, UV protective nor photoenhancing and so there is no reason that changes in irradiance would make any difference to the density of these pigments.

What is a "photoilluminating color pigment"?

[dphins]

Yeah what he said?

[JB NY]

So what would be the cause of acros bleaching when using carbon on a tank? It's quite a common occurance for people who use carbon for the first time to find some of their acros have bleached.

[ATJ]

Joe,

I would have to assume that it is something that the carbon is taking out of the water or something that it is adding to the water that is stressing them.

Do they actually bleach (expel 50% or more of the zooxanthellae) or are we talking death of tissue?

How quickly after the addition of the carbon do they "bleach"?

[JB NY]

Hi Andrew,

No they bleach, most times they will recover their zoox in a few weeks. Normally one can notice the bleaching within a few days. But I have seen, both in my own tank and in others, bleaching associated with adding carbon. Most times it is when no carbon is used on the tank, then one day the person decides to add it and bleaches out their acros.

I'm also not sure I agree that a 25% increase in light will not cause bleaching, or that it is not significant. Going from a 250 watt SE Ushio 10K lamp to a 400 watt SE Ushio 10K lamp is about a 30% increase in light. I've seen many people bleach their corals going to the the higher 400 watt lamps.

[ATJ]

Joe,

Based on my measurements, I don't think you would get a 25% increase in irradiance just by using carbon. The difference from my old water to new water was only 13% and I think that is the most you could expect. Second, the increase is not going to happen immediately and will probably take a few days. That's plenty of time for a coral to photoacclimate to such a small change in irradiance.

Hoegh-Guldberg and Smith (1989) took colonies of Stylophora pistillata and Seriatopora hystrix which had been acclimated to 25% full sunlight and exposed them to 100% full sunlight. That's an increase of 300%. The colonies were much paler than they had been (and than the controls still at 25%) however the zooxanthellae density was unchanged. What had changed was a reduction in the chlorophyll content of the zooxanthellae. They also found that the expulsion rate of zooxanthellae in the exposed corals either did not increase or only increased slightly compared to the controls. Under the current definition of bleaching (loss of zooxanthellae) this would not be considered bleaching and is basically the zooxanthellae acclimating to the new conditions.

The change from 250W to 400W lamps could simply have been an increase in UVR which has been implicated in bleaching.

Hoegh-Guldberg O. and Smith G.J. 1989. The effect of sudden changes in temperature, light and salinity on the population density and export of zooxanthellae from the reef corals Stylophora pistillata Esper and Seriatopora hystrix Dana. J. Exp. Mar. Biol. Ecol..129:279-303.

[ATJ]

Joe,

I should add that I have frequently moved frags around in my tanks such that the irradiance they receive has increased significantly, sometimes more that double the previous irradiance. I've not had a frag bleach under those conditions. I am sure you would have made similar moves in your tank without incident and you have a quantum meter to see how much the irradiance has changed.

[Atoller]

Originally posted by Bomber
Nutrient levels and the type of zoox you're growing will have more to do with it.

Doug, the biggest difference is not only K but MH being a point source and flo not.

Here he goes with his pro-Fluorescent Metal Halide Bad-JuJu again.

[chevell]

.

[chevell]

I wonder here if you have taken into account that your intensity measurements were taken straight below the bulb on the halides, not taken into account the length of the vho bulb. The vho bulb spreads it's intensity out over a much larger area than the halide bulb does and I believe it would be hard to make an accurate estimate on intensity givin that fact.

Originally posted by coralite
Well since I recently got my Li-Cor 1400 data logger and emerged/ submerged light sensor, I guess I'll throw out some quantum lght values at ya'll. JB I know you did a light study not too long ago so you should know where I am coming from.

IMO, sps show fastest growth when receiving 300+ umol/s/m^2

IME this generally equates to 3-6" underwater from vho/pc/t5 that is right above the surface

for a single halide bulb in parallel reflector mounted 6" above the water it is roughly
24+" underwater for 400w iwasaki on m59
<18" u/w for 400W ushio on blueline
<12" u/w for 400w radium on pulse start
<20" u/w for 400w radium on HQI
<14" u/w for 250w radium on HQI

the PPFD will jump as high as 50% for an additional 6-10" beyond the depths I have listed when using 2 bulbs mounted end to end.

For example, you can attain 300 umol/s/m^2 at a depth of 20" when using 2 250W radiums on an HQI.

For the sake of comprehension and clarity, all values are generalized and I assume that bulbs are new and reflectors are clean etc.
For these values let me reiterate that I am speaking about "maximal" stony coral growth rates

[dphins]

chevell, if you have a coral in the center of the tank, do you think having a vho bulb spread out the light over the entire tank will give you more light then a mh above that coral?

[chevell]

Yes under the halide would be higher par just like I just said which is also where the reading for par was taken. Go off to the side a couple feet and then take the reading for the halide and see what you get....less par!

[dphins]

That's why you run one halide per 2 feet. That way you don't worry about the drop off in par from the center of the bulb.