20K double ended question

[StikHedRon]

Does the 20K double ended MH bulb really produce a significantly less amount of par than say a 14k phoenix?

 

[StikHedRon]

Come on folks? No body has done any comparison on this?

 

[dodger745]

I've heard the same thing. I however love the look of the 20k vs. the 14k.

 

[StikHedRon]

I would like to try the 20k's over the 14k's but dont' want to have to lower my lights to the point their right on top of the water surface, to satisfy some of the corals that are sitting in the 450par range.

 

[trido]

I never raised or lowered my MH fixtures when I changed from 14 to a 20K bulb. You shouldnt have to either. You can expect slower growth but better colors from most of your corals f you switch to a bluer bulb. Any pink corals you have ( a hot pink cats paw for example) will be more purple under the 20K. 20K bulbs tend to lose thier intensity faster than a 14 or 10K too.

Having said all that........... I switched from a 250 DE 14K phoenix to a 400 SE fixture and spent years trying to find a bulb that made me as happy as the 14K phoenix. Its really one of the best color balanced bulbs on the market.

 

[Reefing Madness]

Answer is yes. Alot lower. The 14k will also get you much better growth on corals than the 20k will.

 

[nickg]

Yes 14K will give you the best growth. Not sure about the bar readings.

 

[trido]

Answer is yes. Alot lower. The 14k will also get you much better growth on corals than the 20k will.

I've never known anyone that had to move thier fixtures a lot Lower when changing from 14 to 20 K bulbs. In fact most leave them at the same height but knowingly expect slower growth from less par. Most often a reefer is stuck with the height their lights are at due to canopy height or mounting configurations.

I ran my MH lights at about 10" from the water surface to the bottom of the pendant no matter what kind of fixture, wattage or kelvin of bulb. About 14-16" to the actual bulb.

 

[Reefing Madness]

Sorry, wasn't meant to state lowering the light, but the par readings from 20k to 14k.

 

[Mike J.]

As you can see from the charts in this article there is a big difference between 10K and 14K bulbs. Not so much of difference between 15K to 20K bulbs.

Testing 250-watt Single-ended Metal Halide Lamps and Ballasts by Joe Burger - Reefkeeping.com

 

[dodger745]

As you can see from the charts in this article there is a big difference between 10K and 14K bulbs. Not so much of difference between 15K to 20K bulbs.

Testing 250-watt Single-ended Metal Halide Lamps and Ballasts by Joe Burger - Reefkeeping.com

This study was done on single ended bulbs tho....

 

[Mike J.]

I know. I've always wondered about the DE bulbs, too. I know they run hotter, but I don't know about par values. I use single ended 14K myself.

 

[dodger745]

I don't want to hijack this thread, but I'm also looking for the best place to buy DE bulbs

 

[Mike J.]

I don't know about "best", but I do know that I get orders in about two days. Great shipping and customer service.

Bulbs - Metal Halide - Aquarium Lighting - Bulk Reef Supply

 

[Pete polyp]

I know. I've always wondered about the DE bulbs, too. I know they run hotter, but I don't know about par values. I use single ended 14K myself.

There's a huge difference in par

 

[Mike J.]

There's a huge difference in par

Care to elaborate on what the difference is?

 

[Pete polyp]

Usually 150w hqi will compare in par to a 250w single end.

 

[Pete polyp]

This is a good article about the 250w Phoenix 14k hqi

http://reefkeeping.com/issues/2007-04/ac/index.php

 

[StikHedRon]

Very interesting everyone, thanks for you all's input, seems I would be fine with going to 20k but just slower growth. Someone told me that I would have to switch to 400W if I went with 20k's as it wouldn't be enough. Seems their were incorrect.

 

[StikHedRon]

I don't want to hijack this thread, but I'm also looking for the best place to buy DE bulbs

I buy my bulbs at Premium Aquatics, very quick service.