HQI vs. Mogul

[StirCrazy]

Originally Posted by Myka

I have been leaning away from PAR lately...you can get great results without lighting the crap out of the tank. My LPS are all on the sand or the outskirts of the lights (my fixture is designed for a 36" tank and mine is 48" so the halides don't reach the ends very well...perfect for the LPS). They are all well colored. I changed the bulbs to cheap 20K to lower the Kelvin too.

you have to watch that, higher K bulbs don't produce less PAR, but rather PAR that is misread and reported as lower. PAR sensors over report PAR in lower K, IE the 6500K bulbs and way under report the amount of PAR in 20K bulbs. this has to do with the calibration to give you an average PAR level over a wide spectrum.. so by making it report properly under day light when we measure bulbs that have huge spikes of 380 to 420 nm it throws the average off as it isn't calibrated for that range specificly. so because of the nature of blue/violet light it can't read it properly and under reports it. the opposit is tru if you had a huge spike of green, the wave length of green overpowers the sensor and makes it think there is more PAR than there actualy is.

a practical example of this is about 6-8 years ago when everyone was running iwasakies and Ushios, then changed to the new radiums.. the radiums were listed as about 10% less par then the Iwasakis and about the same as the ushios, but people were bleaching corals left and right.

Steve

[Myka]

I don't know about that... red (yellow) light has more photosynthetically usable light than white light does, and blue light has even less. That's like grade 9 biology. I don't know how that applies to aquarium bulbs since there are so many variables like amount of energy put into the bulb and different brands.

[StirCrazy]

Originally Posted by Myka

I don't know about that... red (yellow) light has more photosynthetically usable light than white light does, and blue light has even less. That's like grade 9 biology. I don't know how that applies to aquarium bulbs since there are so many variables like amount of energy put into the bulb and different brands.

there is no white light, white is an effect from combanations of other light colors. thats why there is no white strip in a rainbow.

Photosynthetically Active Radiation or PAR, is from about 380 to 720nm and all forms of light can power photosynthis, the differance is what is more available and what plants have adapted to. If I remember right from hortaculture (corect me if I am wrong) red light will produce a fast growing but spindily plant, where blue light will make a slow growing but stockey plant. we did exparaments growing the plant under blue domanate light for root development and then switched to a red domanat light to increase folage and induce flowering.

Visable light starts at 400nm with Violet, and ends at 700nm with red in between we have blue green yellow and orange

you can produce a white looking light with different combanations of reds, greens and blues (primary colors) this is why we can get different PAR levels from white lights of different brands. one brand might have very high violet/blue and a spike of red and hardly any green and look white, another might have red, green, and blue all at the same levels and it will look white also.

as far as strenght of the wave lenght go the shorter the wave lenght, the more power it has, this is why blue light is domanate in deeper water and the green and red light gets filtered out.

Steve

[HL649]

This has been a very informative thread. Thanks to all that responded.

[Myka]

Originally Posted by StirCrazy

there is no white light, white is an effect from combanations of other light colors. thats why there is no white strip in a rainbow.

Well ya!! Maybe I should have put white in quotation marks for those detailed peoples.

we did exparaments growing the plant under blue domanate light for root development and then switched to a red domanat light to increase folage and induce flowering.

Yes, the sun in the fall is at an angle to the earth, and it creates a red light which is one of many factors in triggering plants of a later season to bloom. Blue light is in the spring, and fades to red as the year goes on.

Lots of information to learn on light, plants, corals, etc.[/quote]