that won't be hard concidering I can make the surface of my tank into a jicuzzi with the two tunze :mrgreen:

Steve

Just wanted to add my comments from the peanut gallery. This method works very well.

Thanks guys. I'm going to try this method.

Mason, I would leave things as they are, you are getting fantastic growth and colour as is... I'd leave it and just make sure your parameters are all in the right place..

I am coming over sunday to wednesday.. I will be in town this time so we should get together.. see ya!



-Adam

You may be right, but I do think that growth has started to slow in the past month. Maybe I'm just getting greedy :cool:

Gimme a call when you get in...and don't forget my table :smile:

Hi Steve,

There a few reasons the test was set up the way it was and not another way.

Measuring PAR values in tank is not the best way of measuring differences in lamps. First, the senor needs to be absolutely level, so you would need to set up a mechanism inside the tank to insure the sensor was kept level. Also, if the sensor is in the tank there is bound to be lots of things amplifying the light being read by the sensor. All reflectors are different, the shape of your tank and the angle of the light entering from where the sensor is, as well as stray light, all change the values. So the measurement you get in no way correlates to what someone else might find using the same lamp as you are testing. Lastly, water quality play a huge role in the amount of light actually hitting the sensor. Someone running a skimmerless system with no carbon would have much less light entering the tank as someone running carbon, skimming heavily and using ozone.

In the ocean higher wavelengths are filtered out as one goes deeper. But this doesn't translate well for lighting over our tanks. Wavelengths of around 550-575nm and lower (which is what most of the light on MH bulbs are) pass almost completely unobstructed in 1 meter of water. It's true that the higher wavelengths of over 575nm can be reduced by as much as 50% in 1 meter. But in the shallow tanks we use in aquariums a lot more of the light irradiated from the lamp is able to get through. Most of our tanks are just not deep enough.

The whole reason the test was done as it was, 8" from the arc tube of the lamp, in a flat black box with no reflector, was to get a reading that had as little variables as possible. Basically you should be able to take my lamp put in the same environment and read the same results. If I were to take a reading of my lamp over my tank and give you the same lamp, you would get a vastly different reading than I.

Personally I think measuring PAR values of the light a coral receives in tank would be a tremendous help to hobbyists. It would help when trading corals as well as when one is getting poor results with a coral another hobbyist is having great success with.

Sorry for the long post.

-Joe

Joe, you're welcome to make long posts here as many times as you like. And it wasn't as long as Steve's anyhow! :razz:

Of course, we like new people to post lots of pics of their stuff, especially new frag tanks! :biggrin:

JB, I loved your test and in no way was trying to slight it as it was very valuable information in my opinion. I was typing a lot and I should have worded it that in adition to the way you tested I want to do tests through water. so i will do both 24 inch of air and 25 inch (6" air and 18" water) the way I am going to avoid the problems you mention is i am going tu build a special testing cylinder to house the water in so my Apogee meter can be fixed in the bottom. this will be filled with clean tap water or fresh salt mix (I am going to try both to see if there is a difference due to the density difference, if there isn't I will use chlornated tap water for the test). by doing it this way I can rule out all the factors you mentioned.

the whole reason for wanting to do this is I found that the inverse square law doesent work when you add water to the situation. I don't expect large differences but I do expect that some bulbs will penatrate better than others.

Steve

:biggrin: WELCOME TO CANREEF, Joe. :biggrin:

Thanks for the welcome! I guess I'll have to post some pictures of my tank now! :D

Heya Doug, thanks for the welcome too!

Steve, No problems, I just wanted to explain my side of the testing. I was getting a lot of heat earlier on and spent lots of time doing various tests and refining the process to satisfy as many questions and potential errors as I could.

I think the water definitely cuts off more light than air. Will be interesting to see what you find. Stray light and absorption will be the biggest factors to account for. Ideally you would want to set it up with no reflector, outside walls of the tank flat black, as well as the enclosure for the lights black as well. I would also either have 8" or 18" inches of air, not 6". That way you can at least compare your results before the water to mine or Sanjay's. There is definitely more to it than just PAR, spectrum without a doubt, plays a big role in the coloration and growth as well.

I wonder if glass reflects certain wavelengths back into the tank? If so, Acrylic might behave differently.