discussion on April's meeting

Laura and Jim will be hosting the May meeting this Saturday the 12th and it will be the usual of food, drinks, raffle and fun.
 
Doors will be open at 6:00 pm for social talk and the meeting will start at 7:00.  Parking gets a little tight and the city says you can't park on 4th but there is a parking lot a block away.   Meeting is usually held in the backyard so feel free to bring your favorite lawn chair, weather permitting of course.

If you need address/directions, contact a club member.

Best if you park at Mini Mall (where the spaghetti establishment use to be)
 
You will get to see his new frag tank set up in the making.
 
Hope to see you there!

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[i1justin]

I thought it would be good to talk a little about things that were discussed at the meeting and if people didnt quite understand something at the meeting they can clarify here again.


I wanted to talk a little bit about lighting which rick talked about. Rick you mentioned % losses due to moving the light source upwards, it was said that moving it up 3 inches and you lost 50% of PAR 9 inches 124% or something. I wanted to question this as i believe these numbers are accurate if you are considering water depth. From what i have learned in some classes and such i feel that such drastic drops would not be due to moving the source in air. The absorbtion and scattering of light in air and water air very different. The amount of light absorbed at the first foot of water is equal to 100s of feet of air!! i do not believe that moving a MH light up 5 inches from your waters surface will cause such a drastic drop, Mikes lights were fixed right? so this was not tested when you were in seattle but the way i see it to be is if you have a 18inch deep tank and then go to a 27inch deep tank you will see that 124% drop. Please converse if you feel i am wrong.

Second i wanted to express my opinion on kelvin ratings and what produces the colors in coral. Light color spectrums are absorbed at different depths. The first color to be absorbed in the water column is  RED, have you ever heard people say "look at your tank with a red light" This is because the red is absorbed so fast in the water column that often the animals dont even know a light is being shone on them. The last color to be absorbed is the blue spectrums. So what does this mean for lightiing? well if you remember correctly when Rick mentioned the PAR levels in the ocean compared to our aquariums there was an astounding difference!
Corals in shallow reefs often use pigmentation as a way of deflecting or minimizing light effects, too much light and the zooxanthellae are unable to photsynthesize. So corals show colors as a means of absorbing certain light while avoiding most of it. So why has the blue spectrum bulbs often showed the most coloration in hobby tanks? Well if you remember about absorbtion, blues are the last spectrum to be absorbed by water. so while the par from MH may be lacking, the amount of blue in the 20k bulbs penetrates water deeper allowing more lighting to reach corals so they can adopt those colors the only get a certain amount of light, I feel that if you were to run a 5k bulb it would be fine, if they were 1000W on a tank not very deep, all the lighting spectrum that those bulbs are heavy in  will be absorbed so quick and there wont be much of anything for corals further down. This is my explanation of what i believe to be the reason behind 20's, i however also feel that visual appeal is a must and 10k have a broad spectrum that is plenty for an average depth tank and actinics have that deep spectrum to help counter and lack of blues in a 10k bulb. If you feel this is wrong let me know, i dont have a PHD in coral ecology or whatever like sanjay, at least not yet.

if anything i hope this made angel feel better about his purchase of 20's
Justin

[angelscrx]

Darn skippy, thanks Justin!

Here's a question mostly for aesthetics though, instead of supplewmenting with actinic VHOs can I use whites to counter some of the blue?  Corals should still get the same amount of light from the MHs but viewing won't be so blue.

[i1justin]

ive seen many people do daylight VHO and some 50/50 and i have used 175W 20k with daylight compacts on a customers reef, works well but like rick said you wont get quite the flourescence out of some of the corals as you might get from an actinic. But the shimmer effect you get is one of blue which is pretty cool, more like what you might see on a natural reef.

Justin

[angelscrx]

Cool thanks.  I have actinics in the ballasts now but have and extra set of whites.  Will have to see when the tank is up and running what it looks like and compare.

[Ed]

Here is some reading for you.   This is some of the things covered in the Meeting in Seattle.

http://www.advancedaquarist.com/issues/mar2003/feature.htm

I am hoping that the distance thing is covered.
Ed

[i1justin]

thanks ed, heres the kicker
"It should be noted here that the light emanating from the reflectors is very different from natural sunlight. Since the sun is so far away from the earth, the intensity at all measured points on a small surface would be identical. This distance is not so for the MH lamps used. These are point sources of light and when placed in a reflector the light emanates in a cone with intensity gradually decreasing as we move away from the central axis of the cone and with increasing distance from the source."

Justin

[Les]

These points are all well taken but, most folks light the tank based on what they want to see for coloration and what grows the corals best for their system. This topic has been discussed until death (in my mind) and we all keep flogging the same dead horse. My preferance is either 65k or 10k bulbs with VHO actinic for the blue spectrum. One of the best color tanks I have seen is dual 400 watt 6500k with two 96w VHO actinics on a 90 gallon. My old tank was lit with dual 10000k with 4 55watt PC actinic. I thought the pc was a little weak and thats why I have changed to VHO. The new tank is lit with 3, 400watt 10000k and 6 96 watt VHO actinic. This is the way it will be until I purchase new bulbs in a year or so.

[Rico]

Justin,

When I first read your post, I too wondered how Sanjay took his measurments (air or water).  Thankfully Ed provided the answer in Sanjay's paper.  Much of his talk incorporated this paper.  And indeed the losses are found when the measurements are taken in the air.  I believe you yourself answered the question as to why with you second respons to Ed.  In this you described the fact that MH lights with reflectors produce conical (or Tee Pee) shaped PAR output curves.  As you can see in the data in Sanjay's paper, there is a significant drop in PAR or PPFD with slight change in either vertical or horizontal distance shifts from the MH bulb.  None of which the human eye would ever see, however knowing the performance of a given reflector could help one place certain corals in the sweet spot of the reflector.  Remember that Light is the primary energy source for corals and clams, so with more photons hitting a coral, the faster it will grow.  As it was stated in the meeting, corals and clams are very tolerant of different light levels and will easily adjust to and grow well with lower than natural sunlight levels.  We are all proving that every day.

I often surprise people when I tell them I have 4 400 MH's running about 6" above the surface and a lot of my corals are from 4 to 8 inches under the surface.  I just move them there slowly and they grow very well.

As for the color spectrum of the lights, last year Steve Tyree left us with the thoughts that the best lighting configuration would be 20K and 6500K MH bulbs side by side in the reflectors.  This being the 6500K provide the necessary light spectrum that is missing from the 20K's, yet the 20k's are providing light in the spectrum that is most useable by the corals.  From his research I believe that is probably very true, just unreasonable for most of us to accomplish.  That being said, we all light our tanks in a manner that is most appealing to each of our tastes.  Some of us like bright crisp white with all other colors showing nicely, and others like Papa Smurf

Eventually I will probably get the Lumenarc 3 reflectors from Pacific Garden supply, just so my corals will grow faster.  The light distribution on the tank now is very good, I do not have any noticable low light areas.

Good discusssion, thanks for bringing it up.

Rick

[i1justin]

i agree, i dont think i posted it clearly but when i saw the difference between sun and MH bulbs i realized what was going on, so 6" it is. Secondly i went to check out the lumenarc reflectors at PGS but all i found i think contained a ballast and ran in the 200 dollar range, do you have a link to the reflector only?
Justin

[Rico]

I just posted several links here http://68.185.37.33/phpbb2/viewtopic.php?t=497

You have to call to get the stand alone reflector price.  Mike O'Brian (Seattle) just purchased several of the deluxe model with glass protection screens and vent hose connections as well as adjustable height sockets so each bulb can be precisely placed in the reflector.  They were $150 ea. with shipping, but it was a small bulk order.

Rick

[Yellotang]

For a long while I grew SPS under my 2 400 watt MH's that were only 3" off the surface of the water. No problem for the corals, they grew great.

Only problem with the bulbs were the moisture would get inside the glass housing during no fired time and crack the bulb when lit.

[i1justin]

Only problem with the bulbs were the moisture would get inside the glass housing during no fired time and crack the bulb when lit.

Thats a pretty decent size problem :shock:

[Yellotang]

Thats when I found out that I needed to install fans that would run at night. Not for heat but for humidity.

[i1justin]

do you still run them 3" off the water? The closer you get the better intensities but there would be loss in dispersal and coverage.
Justin

[Yellotang]

No, I run them 16-18" off the surface now.

Tank of soft corals, no need for the 400's so close.