par levels

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dp1416

what is acceptable levels for different corals to grow? I know this is a vast open question, but in reality i am curious to know what the different needs are.

SPS - generalizing SPS for all types (understanding some are more light demanding) what is a ball park range? If you have 500par on the top 6 inches of water and 120 par on the floor, can the coral survive at 120 or will it acclimate to the 500 just fine?

LPS - same scenario

Zoa - same scenario. I would suspect 50-60 par would be fine for these fellas. I know folks grow them out in pc lights and they grow in my tank in the shade where there is little to no par.
 
Things like flow, water clarity, anything that might affect light penetration would have to factor into your equation as well as water chemistry in general. I think the hobby is too focused on "Get X lighting setup and you can grow this coral." There are too many factors to come up with a general rule that would work for everyone's system.
 
I'm hoping to organize a hobbyist-study with people that have purchases PAR meters, in an effort to see if we can create a database of numbers for particular corals, in hopes of discerning a pattern. It's definitely on my list of things to get started this year, and it will take time to get input from enough people to see if it will be of any value at all.

For most of the easier corals, it seems like 100- 200 PAR is going to work, and for light demanding species, the number can be anywhere between 350 and 800 PAR. When I measure that one A. formosa frag right above the Toadstool, that particular spot is very hot, PAR wise. And the tips are at the surface.

The center of that giant Toadstool is over 400 PAR.
 
well before i through a bi%&$ fit about our par meters i am going to post this here.

I measured my par output and it seemed really low to me with a new 400w bulb. So i called Wes to see if i could compare mine with his. I went to his house and we did a little study on the par meters. We were shocked to see what was happening. We used the same marked spot (eggcrate) in the tank and put the sensors in the exact same spot and found that not 1 of the 3 par meters read the same paramaters. They were off by as much as 32 par points apart. I am really disturbed by the readings and before i bash any product i want to do some comparison tests with others. Anyone that would like to participate or even just send me your par meter ( i will mark it so it does not get confused) we can do a test under different flow, lights, water levels and heights to see what the gap is.

Has anyone else encountered this problem with these Quantum Meters?
 
There can be quite a few factors why you get different readings?

1. How old is your bulbs compared to Wes?

2. Are both of you using the same ballasts?

3. Clarity of the water. One of you using ozone?

4. Are you using the same type and size reflectors? If lumenbrights you have to remembers they focus the light like a flashlight were you measuring exact same spots on both reflectors. one could of been in the "sweet spot" where all the light is focused and the other off.
 
we did the test on my tank only, and out of the water. eggcrate spread across the top of the tank directly beneath the reflector, 15" from the bulb. we marked the eggcrate so we would use the same spot. 2 standard par meters and 1 of the newer ones.
 
Pampee,
We used all 3 meters on wes tank under the exact same conditions. This is where we got 3 different readings. same spot, same conditions...3 different readings. He was running a lunembright with reeflux 12k bulb and blue coralvue ballast
 
the par meters do not have the best quality sensors from what i have been researching good ones run way more than the whole par meter costs

per a light testing website..appogee doesnt even use their own sensors

"Apogee sensor accuracy

There were numerous questions as to the accuracy of the apogee sensor used in the test. To answer questions as to the margin of error that this sensor produced, I contacted apogee and discussed this with them. They agreed to send to me two LiCor sensor that they use for in house for testing. The sensors were first calibrated by them and then sent to me. Measurements were then taken using the two LiCor sensor then averaged to produce a value. The reading from the Apogee was then compared to that obtained by the LiCor sensors. The table below shows the margin of error the apogee was off compared to the LiCor. Also shown is a differential factor. If this factor is applied to the apogee reading, it will correct for any deficiencies of the sensor. As all lamps have a slightly different spectral curve it if different for each lamp."
 
What was the max delta? 32? What was the % variance? Did each sensor read the same value somewhat consistantly? You have the raw data such as (example only) :

Meter 6" Reading 12" Reading 20" reading
Par Meter 1: 400 200 100
Par Meter 2: 362 182 89
 
Charlie
we did see a discrepency and that is why i was asking if there was anyone who purchased the par meter would be interested in doing a more "scientific" trial on the parmeter. I was thinking of using a 150w halide in a 10g tank and set egg crate up on risers and test the meters using the same calculations you were talking about.

Bottom line is if these meters are crap, what was the point of purchasing them. If apogee knew the sensors were not consistent, why bother selling. We gave them a ton of business and they send us this stuff?????

Before i jump on the "we got screwed" bandwagon, i wanted to do some controlled tests but wanted to get at least 10 meters to compare. Even if we get 10 meters and find the delta +/-, we can have an error of margin. Basically saying if your par meter reads 100 par, it could possibly be 120 par based on your actual unit....does that make sense?
 
i have one u can use to test.

when i was comparing mine i turned the power heads and main pump off so water was not moving. i have 3 250w pfo ballast, brand new bulbs and one of the ballast shows more par. i started to look into this more as i just set up another tank 38g and was deciding if my 250w was enough cause i have a 400w ballast also. i was only getting 100 at the top of the water with the 250w.
 
I have one you can test as well.

He is doing a test in an empty tank, so there is nothing to impede the numbers from being consistent other than the sensor being precisely flat on the surface. You may need to screw it to a board, Donnie. Even a slight angle can change the reading. YMMV.
 
Here's a real interesting article on PAR in a natural reef environment, and what kind of light promotes cell division in the symbiotic algae. I really don't feel as bad anymore about switching to bluer bulbs.

http://www.advancedaquarist.com/2009/5/aafeature

PS: A hawaiian reef crest can get up to 2000 PAR of natural sunlight at high noon. I don't think I get half of that at the very top of my tank. :lol:
 
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