Forums / TEAM Marine Depot / Corals and Coral Reefs - by Eric Borneman / How much PAR is too much? / Latest Posts

RE: How much PAR is too much?

Eric Borneman — Sun, 20 Jul 2008 08:02:32 GMT

I don't think it is possible to generalize about all the possible reasons corals bleach in the wild or in tanks. Bleaching is a very generalized response to acute and chronic stresses and the resistance to bleaching is also determined by many things, including species, photoacclimation and type of zooxanthellae being hosted.

RE: How much PAR is too much?

Reefski — Sun, 20 Jul 2008 06:53:22 GMT

regarding bleaching-

i read many posts about people putting a new coral in their tank which bleaches. is it because of the transport stress and being in the dark for so long and the poor lighting of the wholesalers?

it is the point source lighting and unvarying intensity?

if i go out in the sun and spend too long i get sunburned too!

after all in the wild the sun is much more intense than in our tanks. could part of it be that in the sea the illumination is varied. not always so intense, cloud cover, storms, turbulence, turbidity, etc. it may be cloudy, storm for days, or weeks and then bam the sun comes out. and the corals don't bleach.

i am still really enjoying the daily play of the sunlight in the tank.

RE: How much PAR is too much?

Bob the (reef) Builder — Wed, 25 Jun 2008 23:26:28 GMT

Cool will update as soon as new reflectors are up.

RE: How much PAR is too much?

Eric Borneman — Wed, 25 Jun 2008 15:00:14 GMT

All sounds good re: tank.

Miscommunication on the weather - I guess I have been paying a lot of attention to it now since we have had ridiculous tornadoes and flooding in the middle states and it is hurricane season for us so my eyes are on the tropics now, too.

Thanks for the SA update. Sorry for your neighbor but glad not only the xenophobia has diminished but that there were actually discussions. How novel for a lot of countries!

RE: How much PAR is too much?

Bob the (reef) Builder — Wed, 25 Jun 2008 08:50:02 GMT

Hi Eric,

Thanks for the local, Houston and US weather report, but the freakish weather I mentioned was that that you had in the biggining of your visit to SA. I guess it could be taken either way. What I meant was that our weather through the winter months is usually cloudless and rainless.

So their was no cloud to interfere with the readings. What I plan however is a sort of a simple sun tracker. Imagine taking the full 1980par of light and bouncing it straight down the chimney I recon I can at least double these preliminary readings.

Regarding the mad dictator north of us, well he seems to be slipping more and more towards lunacy every day. Have you seen some of the outfits he now wears to political rallys. Circus clowns would consider them a bit over the top.

Apparently when mad Bob lost to Chvangurai in the recent ellection, he was prepared to stand down, but was held under house arrest for a week or so by his top military guys, until he was persuaded to resist handing over power. His top cronies all have a lot to lose including their freedom if he loses power.

I was told that by an old school buddy now living in Zim, and also much the same from some well connected political Zim commentators in SA.

Our local Xenophobic outbreak seems to have dissappeared, with much discussion on how to avoid it in future.

Cheers

Rob.

RE: How much PAR is too much?

Eric Borneman — Wed, 25 Jun 2008 06:16:49 GMT

Hi Rob:

The numbers look great except in the afternoon where the fall off is strong and longer lasting than ideal. Those numbers are great for winter solstice. Is there any way to use a sun-tracker to try and ameliorate the drop. Such an effort might also be used to drop levels in the summer if they get to high/hot by off-positioning the amount of light. I am sure it will work, but given your dedication and investment, it seems worthwhile to look at feasible optimization.

Was there noticeable cloud cover after those midday reading that would account for the drop?

Also, we haven't had any freakish rain. In fact, we have been watering a lot. Lots of typical tropical/subtropical patchy short-lived afternoon thunderstorms, but otherwise a normal hot humid early summer. The horrible storms and rains are up north n the midwest, and it is almost 1300km north of Houston just to get to the northern border of Texas and that is still south of where some of these storms have been happening. Houston is essentially on the Gulf of Mexico in the lower SE corner of the state.

Also, trying to keep up on the Zimbabwe situation. Sounds awful and news from SA has virtually disappeared in light of the developments that now focus almost entirely on Zimbabwe. How are things there?

Glad you got the Apogee. Fun, no? Have you let any others borrow it? I'm sure there are going to be some surprises. I wouldn't be surprised if Carl actually has the highest PAR of the tanks we saw due to those reflectors, and make sure for anyone running double-ended to show how much the PAR changes horizontally with those fixtures/reflectors. I think you will open a lot of eyes!

RE: How much PAR is too much?

Bob the (reef) Builder — Tue, 24 Jun 2008 07:44:49 GMT

I finally got my Apogee light meter.

Our winter solstice was two days back.

I took a bunch of readings today (clear blue skies)

I took a high reading (where top corals will be) low reading (bottom of tank). Bear in mind I have no tank yet but 800mm of water instead of air probably won't make too much difference I think.

8am..Hi 55..................................... outside -

.........Lo 40

9am..hi 100-120........................................650

........lo 50- 75

10am.hi 150-190.......................................820

.........lo 65-115

11am.hi 260-311......................................1180

.........lo 140-212

12am.hi 280-371......................................1200

.........lo.150-250

1pm...hi 190-290

.........lo 150-200

315pm 100-110

..........lo 50- 65

What do you think for mid winter.

I am going to put in two reflectors in the gable to take the direct sun (if I point the sensor at the sun it reads 1980) and bounce it straight down. This is so that the 45 degree sun dosn't need to bounce 6-7 times to get down the chimney. I think it should make a very big difference.

Rob.

RE: How much PAR is too much?

Bob the (reef) Builder — Thu, 29 May 2008 00:03:23 GMT

Eric, you just experienced freakish unseasonal rain. We normally get virtually no rain and totally clear skies for the next 4- 5 months, which is good as this is when we will also be getting the least light (winter).

We get our rain in the summer months. So far the chiminey is still supplying good light. (looking forward to my Apogee in a week ir two.)

RE: How much PAR is too much?

Reefski — Wed, 28 May 2008 09:20:25 GMT

yes 34 degrees. and 15" of rain average. although we do have many overcast mornings for 2-3 months this time of year. today however dawned sunny and beautiful. the kind of day that makes 12 million of us or whatever it is want to live here.

RE: How much PAR is too much?

Eric Borneman — Wed, 28 May 2008 06:57:00 GMT

He's about 26-27 S. Houston is 29-30N, and you are what 34N? But, it rains a lot here and in Jo-berg, not so much in LA.

RE: How much PAR is too much?

Reefski — Tue, 27 May 2008 13:21:01 GMT

what is your latitude?

right at the moment the light is coming directly down the shaft into the tank.

RE: How much PAR is too much?

Bob the (reef) Builder — Tue, 27 May 2008 12:33:06 GMT

Once the tank and then the bulkhead from there to the ceiling are in place , I will be able to fix it properly. May replace the bubble stuff (from tank to ceiling +- a meter) with proper aluminium reflective material for its more structural qualities.

Regarding the bubble materials ability to handle salt water, I don't know, other than it is plastic coated. Maybe being a meter off the water will turn out better from this perspective too.

RE: How much PAR is too much?

Eric Borneman — Mon, 26 May 2008 06:30:52 GMT

Rob:

Were you planning to stabilize the bubble-wrap like material with anything or keep it rather draped over the tank from the ceiling down? Do you know how well that mylar-like material will hold up to salty air?

RE: How much PAR is too much?

Bob the (reef) Builder — Mon, 26 May 2008 00:50:07 GMT

The reflective material used is a plastic coated aluminium, which is attached to a tough plastic bubblewrap like base. It is used in insulation of industrial roofs, and is fairly inexpensive.

I got it more by accident than design but its slightly bumpy surface, which causes some diffusion works nicely.

I thought I would add two baffles in the gable part (see pic) of the skylight so as to catch light as it enters the chimney and direct it straight down. I thought of hinging them at the top, so that with a pulley, attached to the bottom of the pipe, I can alter the baffles direction depending on that months sun. It varies from straight up to about 45%.

I will start a thread.

Cheers Rob.

RE: How much PAR is too much?

Reefski — Sun, 25 May 2008 07:55:15 GMT

Rob, no offense taken. the light is distributed more evenly than you think, at least over the course of the day. although at any given time there may only be an area that is brightly lit. at mid day the tank is pretty evenly lit. i have thought of adding baffles inside the shaft but it seems like a lot of work and it would make it harder to work on the tank too, which is going to be difficult enough. and i may have some lights over the tank eventually.

most corals on the reef are also shaded during different parts of the day.

i am at 36-37 degrees latitude here in los Angeles. although the days are shorter and the angle of the sun is less we still have many sunny days in the winter. actually probably more than at this time of year. this time of year we have most day for the next couple of months start out overcast in the morning and then it gets sunny by noontime. i am about 3 miles from the beach.

i would like to see you start a build thread so we can follow your progress. i am very interested to see what you do.

what are you lining your shaft with? what is the size of the shaft and tank?

RE: How much PAR is too much?

Bob the (reef) Builder — Tue, 20 May 2008 23:43:33 GMT

Yup, Carls planning had you staying, he just neglected to tell you guys. Had a whole fridge of veggies too.

Regarding the light meter, I have my Appogee on the way, one that can do sun and electric light. I will really need it with placement in this tank.

RE: How much PAR is too much?

Eric Borneman — Tue, 20 May 2008 04:14:41 GMT

Rob, you bought us roses? We had no idea! Thank you.

The use of a potted plant that thrives in bright sunlight is probably not a bad way to pre-assess light. I hadn't though of that before. Not as accurate as a PAR meter, though. Rob, you and some of the guys in Jo-berg really should pitch together and buy an Apogee PAR meter and you can all use it since you don't need to be measuring all the time. For you, especially, it would be really helpful in "tuning" your light especially with your proposed use of the gels.

RE: How much PAR is too much?

Bob the (reef) Builder — Mon, 19 May 2008 00:43:42 GMT

Carl, my last post seemed a little critical, it was not intended to be, I hope it was not taken that way.

A possibly interesting observation.

A vase of roses, bought for Eric's visit, and placed in the big void where the tank will be, is now three weeks old. Normally we're lucky if they last one week.

I put it down to the fact that its getting good light, the leaves are photosynthisysing, and they have energy to open up properly, yesterday after virtually three weeks two flowers opened up beutifully.

I don't know how exactly that translates to success with corals, but both roses and many corals need lots of light.

RE: How much PAR is too much?

Bob the (reef) Builder — Sun, 18 May 2008 07:44:22 GMT

Carl,

I am fairly certain that if your reflective material does not go down to the top of your tank, by mid winter you will have a well lit living room but none in the tank even at mid day.

At my latitude, mid winter sun comes in at 45% at mid day. You will almost definately be further from the equator. Thus with your reflector 400-500mm off the tank, even a meter wide tank will get its side glass lit, and the rest on the living-room floor.

I think that as well as this you need to think about fins in the shaft to defuse the beam a bit, or you will always have half the tank brightly lit and the other with only very little light.

I think that you reflective material is doing too good of a job with your beam of light, and that it needs to be broken up a bit.

With adjustable or even non-ajustable fins at the top you could angle them so that light is not bouncing around the tunnel so much and heads more straight down.

RE: How much PAR is too much?

Eric Borneman — Fri, 16 May 2008 12:03:29 GMT

For reefs worldwide the average is 82.7-85.1F and this includes outliers (high latitutude, etc). The center of coral biodiversity is what Chuck mentions and this is also where most of our corals come from.

The story of transplantation studies, interrelationships with light and temperature and salinity, variations in thermal tolerance/acclimitazation, ability to upregulate hsps, symbiont variations, across space and time, and other points Mike makes are valid, but not written in stone. May corals, even in areas of high average annual temps may experience warming and cooling far above their norms without obvious detriment (upwellings, lagoons, thermoclines, etc.). There are synergistic effects with temp, and clealry seasonal variations (high lat reefs can become quite cold in winter and quite warm in summer - generally hotter and colder than more equatorial reefs.

I do agree it is largely a matter of holdover from years past, and I also think that if temps are very stable there is not necessaily less wiggle room for some species, but if variations in the tank are normal, I think there is. And an upper thermal limit can be established although it too varies according to place - in the example Mike uses, Pocillopora, Eastern Pacific and Easter Island reefs have low tolerance for temp increases and would not do well if put into the 88-90 water where they are also found (i.e. area of the Red Sea, central I-P lagoons with low water flux). Same species, different "wiggle room" but perhaps able to be acclimtized over time.

RE: How much PAR is too much?

Reefski — Fri, 16 May 2008 10:18:09 GMT

i am reading " A Reef in Time" by J.E.N. Veron right now. he states that the ideal reef temp is 27 degrees C which translates to 80.6F this is for the GBR and he says "for all metabolic processes, photosynthesis and calcification proceed at an optimal rate at this temp. if the temp is higher than that, the rate of these metabolic activities is accelerated in an increasingly uncontrolled way."

great read btw. i still have a lot more pages to go but i am starting to feel even more guilt about my contributions to global warming than i was.

a lot of science but written so that even i can understand it so far.

RE: How much PAR is too much?

greenbean36191 — Fri, 16 May 2008 08:59:49 GMT

Ugh, the inability to edit posts is frustrating.

Meanwhile the same species in my personal tanks would rarely see summer temps below 82 without issue.

As it's written this is confusing. What I meant is that it was rare that these animals in my personal tank would see temperatures below 82 during the summer and there were no obvious issues. In constrast, the animals I work with show severe stress at 82 which is about 4 degrees above their normal summer maximum and kept at that temp long enough they bleach.

RE: How much PAR is too much?

greenbean36191 — Fri, 16 May 2008 08:55:03 GMT

The only argument I have made and I think is valid (others also mention this) is that reef corals often live near their upper thermal limit and by running tanks warmer, there is less of a safety margin.

Yeah, but the thermal limit changes with the ambient temp, even on a seasonal scale. I really doubt keeping the tank on the cooler side actually provides any more wiggle room. The people reporting problems at 82 or so suggests that it doesn't. I use BTAs that come from a reef that sees summer maximums around 78 so I only have to crank the temp up to about 82 to do stress tests. People have done the same with Pocillopora from the same reef. Meanwhile the same species in my personal tanks would rarely see summer temps below 82 without issue.

The best explanation I've seen for keeping temps cooler is that its just a holdover from the days when livestock from FL and the Caribbean dominated the hobby, so the upper 70s was closer to the natural temps where the animals were coming from. 78 was already established as the "ideal" temp by the time the majority of stuff started coming from the Pacific, so it was hard to convince people to change, especially when their books said 78 was great. It also doesn't help that the reefs that are closest to most forum users are also some of the coldest ones (FL, Bahamas, Hawai'i for Americans and the northern Red Sea for Europeans). If they're among the few who have actually been to a real reef, they're likely to have a skewed idea of what "typical" reef temps are like.

RE: How much PAR is too much?

Bob the (reef) Builder — Fri, 16 May 2008 02:34:23 GMT

Wow! worked first time. Amazing considering the horribly poor level of computer funtionality I usually exibit.

Some more pics then.

The skylight needs work (needs a proper roofing dude like Carl) but its big and lets in plenty light, the gable faces North (where our sun is) and also has reflective surface to direct sun in.

This is the gel filter I will probably use. It dosn't limit the spectrum, just cuts out a % of reds, yellows and some greens.

RE: How much PAR is too much?

Bob the (reef) Builder — Fri, 16 May 2008 02:25:06 GMT

Ah, so you guys don't sleep, might make communication easier.

I will try to put up some pics

This is where the tank will be, reflective material will be right down to top of tank, if I can manage it.

RE: How much PAR is too much?

Reefski — Fri, 16 May 2008 02:11:57 GMT

ah, i see i am not the only insomniac, although i suspect Eric is only suffering from jet lag.

welcome Rob, i am looking forward to seeing some photos of your progress.

the skylight tunnel is 12-14 feet from roof to tank.

the material is made by anomet, http://anomet.com/cgi-bin/online/storepro.php and is the Anolux III in 4x8 sheets

the whole tank build thread with more pictures is here.

http://forum.marinedepot.com/Topic70159-13-1.aspx

RE: How much PAR is too much?

Eric Borneman — Fri, 16 May 2008 01:49:30 GMT

Nice to see you here, Rob. I was curious about the latitude, the height, and the materials of the tunnel, too.

RE: How much PAR is too much?

Bob the (reef) Builder — Fri, 16 May 2008 00:38:49 GMT

Hi Eric, Carl

Its that guy from Africa, Rob.

Thanks Eric for suggesting I pop over to see whats happening.

Its great to see someone doing something so similar to what I am. I saw the build forum a while ago. It's good to see the tank up and running.

Well done to you Carl I wish mine was ready to take water, but I had some hassles getting the glass bent.

If I may ask. How high is your light tunnel?

What state/latitude are you on?

Looking forward to interacting with you guys. When you wake up that is.

Rob.

RE: How much PAR is too much?

Eric Borneman — Wed, 14 May 2008 21:31:26 GMT

>>as far as temps go why do you think most people run their tanks at much lower temps than Chuck says are the lows he experiences?<<

repetition of aquarium truisms without basis? Because someone told them so? I don't know. The only argument I have made and I think is valid (others also mention this) is that reef corals often live near their upper thermal limit and by running tanks warmer, there is less of a safety margin. That said, if there is a malfunction that results in tank overheating, it generally goes way above reef temperatures. However, if there are a lot of other stresses and temperature is high, there may be less room for other stresses. But, if you are a competent aquarist as you are, and barring malfunctions or other acute problems, I would say run your tank at reef temperatures.

>>why would i want to use a tinted filter over the tank? i understand the attenuation that occurs in the ocean, however using a certain colored filter, wouldn't that limit the wavelengths to just one? wouldn't the corals benefit from the wider spectrum? <<

No, if you look at all the gels, you can get ones of varying transmissions. I think these are better than "screens." These I mention in case of periods of extended and very high light levels, acclimation, variation, etc. I mention the colors only if you wanted a slightly different color than pure sun. I personally have no issue with the look as it looks like reef to me and the blue-look tanks look fake...even in deep water reefs don't look like tanks lit with blue/20k type bulbs. But, it's an aethetic thing and a potential solution even if you want to only slightly change the look - or dramatically.

>>i know people will criticize the browner colors without the blue 14-20k bulb look. the bulbs may put out more spectrum than the filters too. what do you think? i too like the pretty colors but want to run the tank without much if any supplemental light if possible.<<

I'm all about your plan and any criticism would be put to rest with a simple show using light high in exciting fluorescence. I wouldn't care less about what others think or like. You'll also still have colors - and they will be natural, and not an illusion.

>>as far as the colors go if the coral is receiving the maximum light that it can handle won't that encourage whatever color is there whether it is perceived as really blue or green or whatever?<<

for some yes, for others not so much.

>> or does the light tending more towards the 6500K range actually change the colors exhibited or encourage higher levels of zooxanthellae?<<

Not at all.

>>or does photosaturation change or diminish the color?<<

again, no one answer. yes it can change it, perhaps enhancing, perhaps changing the perception, perhaps reducing. Depends on the role, if any, of the color pigments.

this is a very interesting topic to me.

i do have some of the 4x8 sheets left that i could build a supplemental reflector above the roof with but wife and neighbors might not understand or approve. and it would have to be substantial not to blow down in the first windy day.

it would be interesting to see photos of what the guy in africa is doing.

i will continue to take readings periodically throughout the day and year.

did you see my build thread in the tanks forum? http://forum.marinedepot.com/Topic70159-25-1.aspx

RE: How much PAR is too much?

Reefski — Wed, 14 May 2008 14:06:49 GMT

eric: this brings up more questions-

i am very excited that i will be able to run my reef with sun power, directly and through the photovoltaics. right now we are generating about 65 Kw per day from our 10 Kw system.

as far as temps go why do you think most people run their tanks at much lower temps than Chuck says are the lows he experiences?

why would i want to use a tinted filter over the tank? i understand the attenuation that occurs in the ocean, however using a certain colored filter, wouldn't that limit the wavelengths to just one? wouldn't the corals benefit from the wider spectrum?

i know people will criticize the browner colors without the blue 14-20k bulb look. the bulbs may put out more spectrum than the filters too. what do you think? i too like the pretty colors but want to run the tank without much if any supplemental light if possible.

as far as the colors go if the coral is receiving the maximum light that it can handle won't that encourage whatever color is there whether it is perceived as really blue or green or whatever? or does the light tending more towards the 6500K range actually change the colors exhibited or encourage higher levels of zooxanthellae? or does photosaturation change or diminish the color?

this is a very interesting topic to me.

i do have some of the 4x8 sheets left that i could build a supplemental reflector above the roof with but wife and neighbors might not understand or approve. and it would have to be substantial not to blow down in the first windy day.

it would be interesting to see photos of what the guy in africa is doing.

i will continue to take readings periodically throughout the day and year.

did you see my build thread in the tanks forum? http://forum.marinedepot.com/Topic70159-25-1.aspx

RE: How much PAR is too much?

Eric Borneman — Wed, 14 May 2008 11:16:42 GMT

No, I am sure some could or will be photoinhibited, but so are many in tanks with bright metal halides. They are used to it in the wild.

RE: How much PAR is too much?

sjames — Wed, 14 May 2008 06:37:40 GMT

in the spirit of "how much PAR is too much" I have a question.

Is photoinhibition a moving target? Or is this a fixed number for the specimen in question?

Based on the numbers Ive seen, the OPs corals would be well into photoinhibition during peak daylight hours. Will that always be the case or will they adapt to the light levels and at some point only be at saturation?

RE: How much PAR is too much?

Eric Borneman — Wed, 14 May 2008 02:16:04 GMT

Chuck wrote:
" Such a temp swing is perfectly normal, and would be more concerned if there were no swings. Stable to me equals stagnation, and stagnation in everything is never a good thing. The reefs see such swings every day, some more or less in degree. If I enter the water and am out on the reefs at high tide, I could tell you when the tide is changing by just feeling the "hot" water rushing down the reef from the reef flats that have been cooking under the sun all afternoon and easily reach 90, if not more. But even without such flushing, the lowest temp I have ever recorded on the reef (average 40' deep) is 82, with high averages at 86. Again, the thing about temp is that the corals are acclimated to it, which they need a great deal of time to adjust to. They can easily handle sudden rushes of warmer water for a few hours, but its the long term average temp that will make or break them. Say the reef (or tank) runs at 78 on average, then you flush it with 84 degrees and it cools back down over a few hours back to its 78 average, thats no big deal, but if I were to jump it to 84 and keep it there for a few weeks, I would expect the corals to bleach."

I couldn't agree more! EXACTLY!

Reefski:

Bless you for using photovoltaics. Not sure if your budget allows, but there are mechanical sun-followers for solar panels, and you could probably figure out a way to do something similar for the winter months to capture and channel the lower azimuth during those months with another tunnel-like piece above the roof, even if mechanical and moved every couple months.

Yes corals are grown in more northern latitudes, and sometimes supplemental light is used and sometimes it is not. I think Steve has a case of more than enough light and perhaps too much, while others not so careful about their placement, materials, and cleanliness of the ceiling have an issue with too little and need supplemental. My sunroom, for example, has double pane standard glass and the outer glass is etched from acid rain and calcium deposits, or has leaves on it during parts of the year, and a large tree shades part of it. Despite being visually a very bright room with glass walls and ceilings, the PAR inside is very low and in the tanks even lower. High enough to keep corals alive but definitely not high enough for anything approaching adequate light.

RE: How much PAR is too much?

Eric Borneman — Wed, 14 May 2008 02:07:09 GMT

>>
i wonder if i can't just leave the three sides open that last two feet. i hate to waste the light though and it would hide the returns around the top of the tank that will go in when i have a sump.<<

I'd hate wasting it, too, and you should be able to control temps with fans - or a chiller - and heaters.

>>the sump should be able to help with the heat some. it will be a few hundred gallons in the garage wich is partly below grade,<<

good plan

>>i too am a bit concerned about acclimating corals to the temps and the higher light levels. i have had some of them lighten up after going in the tank. Monti caps, both green and orange that were 6" under a 400 watt halide turned pastel at first but have now started to get a bit darker now and are resumming growth. about 6 weeks in the new tank.<<

Sounds normal

>>what do you think about the swing in the temp of 4 degrees over the day? the 86 degrees was only with our recent near record temps for this early in the year. we will have temps this high again but not for a while. temps should be about 20 degrees less today. <<

4 F is fine and tolerable. 4 C not so good.

>>up until this past weekend the tank temps have only been running around 79-80. so that is a big jump suddenly over just a day or so. all looked well last night although it is still early here and i haven't looked in on them yet today. i do have a flashlight by the tank for after dark viewing.

how much daily variation can they take?<<

Normally, what you are experiencing is fine. Are temp swings normal? Yes in many areas. Are they stressful? Yes, to some degree but many will likely acclimate without issues.

>>i have a 2hp chiller on order and think i should have it for insurance. i wish i could figure out a way to use the 1200 gallon cistern in the ground as a heat sink through an exchanger. <<

The cistern would be wonderful provided it doesn't grow things inside or through the outflow you don't want. The chiller, in this case, is a good idea. You may also want to look at Rosco screen gels in various opacities to shade or change the light color as needed or if needed. (http://www.rosco.com/us/products/lighting.asp)

>>should i enclose the other three sides to capture more light that would more evenly light the tank?<<

I would - and would use fans to exhaust heat. Probably this is too big a job for the little 4" computer fans used in hoods. I would probably use a real fan - nothing major unless needed - like the Vornado-style.

RE: How much PAR is too much?

Eric Borneman — Wed, 14 May 2008 01:58:44 GMT

>>the last two feet of the shaft is open on three sides and a lot of light spills out. i like the access but think i should continue the reflective material down to the top of the tank.<<

I agree, unless you get too much heat.

RE: How much PAR is too much?

Eric Borneman — Wed, 14 May 2008 01:57:39 GMT

On your readings:

This appeared to be a perfect day and I agree with Chuck it seems very natural. This is a nice amount of clouds in the photo - very typical for tropics, too, although the azimuth may have dropped it a little and the photoperiod may be a little off, but overall perfectly acceptable. I'd do this a few more times on various days with different cloud covers, clear skies, rainshowers, and periodically over the year for seasonal changes. You will really know what light is like then. Looks great so far. I would also do this not just above the tank but outside so you see the changes based on having early and late lower levels becuase of the tunnel effect of the light. I just met a great person in South Africa who is doing something very similar with a new tank and will try to get him involved in this thread as I think all will benefit from the comparison and results over time.

left middle right
7am 22 22 22
8am 148-160 44 44
9am 56 125 375-410
10am 80 130 160
11am 240-250 290-300 140
12pm 800-925 500-550 350-400
sun came out for a bit just after 12pm but was partially cloudy by 1pm again
1250-1400 800-850 600-700
1pm 90 550-650 1000-1100
2pm 100 250 800-900
3pm 200 150 70
4pm 95 105 65
5pm 60 80 65
6:30pm 15 15 15

RE: How much PAR is too much?

Eric Borneman — Wed, 14 May 2008 01:51:44 GMT

I saved this post because I knew after reading what transpired in my absence it would take some time. I'm going to do this in a few installments now as I go back and cut and paste parts of previous posts.

RE: How much PAR is too much?

Reefski — Tue, 13 May 2008 14:26:11 GMT

Eric-

any thoughts about my setup. so far all seems well.

on a recent very sunny day peak PAR values were off my Apogee meter. of course other parts of the tank were only 4-500 at that time.

RE: How much PAR is too much?

charlesr1958 — Tue, 29 Apr 2008 16:24:32 GMT

I'm not familiar with Anthony's greenhouse but have seen online photos of others that appear to have large MH units hanging over the tanks/tubs and assumed they were there to supplement when and if needed. With having your own PAR meter I guess in a few months you will find out if you need to supplement or not. If the readings do not drop drasticaly I would not bother with extra lights as any slight or moderate drop will be very gradual and something the corals can adapt to. They might brown up on ya a bit but I personaly could care less what color my corals are or become as long as they are healthy and growing.

Chuck

RE: How much PAR is too much?

Reefski — Tue, 29 Apr 2008 12:08:35 GMT

i will eventually have to leave the room if only to check on the sump in the garage below. that and get food for myself and the tank

the winter sun does concern me. but because of the direction the slope faces and the fact that we are on a small hill with no neighbors houses shading our roof at all it is the best it could be. i hope that is enough. people come over and want to know about night time viewing and will i have lights? i tell them not if i don't need to. i hand them a flashlight and tell them about all the interesting critters that only come out at night.

so maybe i will have lights that i run over the tank just in the winter time for 4 months, we shall see.

i wonder how i would tell if i wasn't getting enough light? didn't anthony Calfo and many others have greenhouses growing corals in much more northern latitudes than i? do they use supplemental lights?