3000W @ 20,000k MH how much Actinic?

[Mouse]

3000W @ 20,000k MH how much Actinic? Thats the question, its going over 336 gallons, 6ft long, 2 1/2ft wide, 3ft deep. should work out @ just over 7w per gallon. Its going to be the SPS penthouse. But im not sure how much Actinic to use, i really like the idea of PC bulbs for this. Any pearls floating about?

 

[MicroChip]

Sounds to me like 3000W of actinics are already going over the tank, since that's what 20,000K bulbs basically are...

If you were using 10,000K or 6,500K I'd say about 110W of VHO actinic or 96W of PC actinic per 400W of MH is usually enough.

 

[MiNdErAsR]

Personally I'd choose 10,000°k bulbs over 20,000°k. But that's just me. Either way, I don't think you'll need any actinic lighting with all that blue. If you must have that extra blue look, why not try some of the new Iwasaki 50,000k (150w?) halide bulbs? I think they'll do a better job over a 3 foot deep tank then any PC bulb could hope to do.

BTW, watts per gallon is as useless a "rule of thumb" as bubbles per minute or inches of fish per gallon. Watts per square foot is a little better, but not much.

Sounds like an interesting project. I hope there will be photo-documentation throughout the process of setting up this system. Anxiously awaiting the final outcome.

 

[jdeets]

You won't need any actinic with that Kelvin rating on the bulbs. I'm using 10000K MHs over my 180. They are plenty blue. So instead of VHO actinic supplementation, I'm using VHO 50/50s to get more white light into the tank and make the color a little more pleasing. The actinics, even with the 10000Ks, made it WAY too blue.

 

[monkeyboy]

Yep i think MicroChip hit it right on the head. You are putting 3000w of actinics over this tank. I would go with 10000k or 6500k halides. Since these 20k bulbs are so blue you lose much of the PAR, giving you much less intensity than if you went with 6500k lamps. I would probably do 10k's because you'd need a large number of VHO actinics to color up the 65k's. Just my 2 cents.

 

[Mouse]

Cheers guys for the info on the lights, allthough all of your suggestions are great i still cant figure out what to do. If i go for the 10,000k or 20,000k bulbs then it seems i dont need any additional lighting. My only concern in this case would be shocking the fish when they get turned on in the morning. And also how i regulate the lighting throughout the day when using 3 x 1000w bulbs. Do i have all three burning for 14 hours, do i have 1 come on in the morning for 2 hours and then turn the others on after that. What happens to the corals directly under the one bulb that gets turned on first? Also will the 10,000k & 20,000k bulbs cause the corals to Bioluminesse (glow) like they do under conventional Actinic bulbs. The lights i have available do have a moonlight option, this will be variably controlled by the computer. Should i use these moonlight bulbs to create the two hours of dawn and dusk by having the computer turn up the power of them slowly.

 

[jdeets]

MH lighting generally won't "shock" your livestock when it comes on because it takes a good 10 minutes for them to warm up. When they come on, they glow faintly and gradually go up to full power. Many people actually have their MH come on first and the VHO later, because the fluorescent tubes coming on instantaneously are more shocking to your livestock than the MH.

As far as not needing VHO supplementation, I'd consider the 10000Ks over the 20000Ks. The 10000Ks have a really pleasing color. If I had the foresight to use 400W MH over my tank instead of the 175s, I wouldn't even have any VHO supplementation because IMO 10000K is a really nice color by itself. Since I need more light and have to use the VHOs for extra intensity, however, I went with the 50/50s because the actinic VHOs were too blue in conjunction with the 10000K MHs.

As far as having them come on and off, you could have the middle come on first and the ends come on 30 minutes later or something like that. Also, have them shut down in stages at night so that all of them are on for the same length of time. That way, your fish aren't left in the dark instantly and as the lights go out one by one, they'll learn that it's time to seek out their sleeping quarters for the night.

HTH

 

[MiNdErAsR]

I would suggest a sunrise/sunset effect by timing the lights to come on gradually, reaching a peak with all lights on, then gradually turning off in reverse order. Each bulb burns for 8 hours, but staggered for a more natural appearance. Adjust as needed for your desired photoperiod. For instance, halide 1 comes on at 8am, halide 2 on at 10am, halide 3 on at noon. Then reverse order, halide 1 off at 4pm, halide 2 off at 6pm, halide 3 off at 8pm.

IMO

[ September 08, 2001: Message edited by: MiNdErAsR ]