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#1
11/29/2005, 12:57 PM
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Switching from PC to Metal Halide / VHO question
Right now I have Dual 65W (10,000k and Actinic) Coralife PC fixture. I'm looking to switch to metal halide lighting / VHO. This is for my 20 gallon high reef tank since my PC is limiting me from keeping some things. My question is what type of Metal Halide fixture should I use (watts? wise) and do I need to be concerned about the heat from them? My tank is at 72 without the lights on and peaks at 75-76 before they go off.
Also will the metal halides burn / kill my critters / corals? Here is the list: 2 Trachphyllia Geoffry (Open Brains) 1 Maze (Worm) Brain 1 Candy Cane 1 Pagoda Cup 1 T.Deresa Clam 1 Clarkii Clown. 1 Cleaner Shrimp Coupler Astras, Nassarius, and Scarlets Here is the pic of the tank to get an idea of what it looks like (lights just turned on so everything is openeing now): 
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#2
11/29/2005, 01:39 PM
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You definitely want to carefully acclimate the corals slowly to such an increase in light. At a minimum, you will want to move them to the bottom. An even better alternative is to raise the actual fixture and slowly lower over the course of weeks/months to acclimate them. This should help keep many from bleaching, though there is no such guarantee. Just go about it carefully and cautiously.
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#3
11/29/2005, 03:00 PM
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I am looking to upgrade too... I have a 20H too. I am thinking to do a retrofit kit MH between 150-250 (haven't decided yet) Was wondering too on the the spectrum and the wattage.
New questions are what type of ballast for DYI... electronic or magnetic (pulse or probe start)? I was going to build a canopy along with this and I can post up plans if I do so for you to look at too. The corals are a worry though and I think I will put them on the bottom and under the overhang of rocks too to slowly bring them back up. Though all my corals are at a friends recovering from some noob mistakes I made  I will be following this with you  The heat will be an issue too... mine is 78day / 77night now with 80watt PC fixture... I am going to add a few fans to the canopy to help out with air flow and probably convert a 10g tank to a sump for easier water top off with the increased evaporation and to move some of the noisemakers off the side of the glass 
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#4
11/29/2005, 03:29 PM
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Since the tank is in my basment and I have central air, heat in the summer is not a problem, just the winter since my house is Steam heated.
I do however have a Tile cealing with braces that run back and forth and can easily raise and lower the light. What type of Metal Halide / VHO should I get? or should I retro fit my Coralife twin 65W. |
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#5
11/29/2005, 04:21 PM
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a single MH pendant with a 10,000K 250-watt bulb raised above the tank with actinic support from a fixture with either VHO or PCs would be a good choice for your 20-gallon reef. I'm not certain how deep the 20-gallon high is, but you could probably also use a 175-watt MH if it isn't deeper than about 19 or so inches, unless you're intending to be stocking it with mostly SPS. Having a fan blow across the top of the tank between the pendant and the top of the tank should prevent too much heat transfer to the tank, though the room might get a bit warmer than you're experiencing now.
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#6
11/29/2005, 04:32 PM
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A 20H is ~24in deep... so should a 250watt be used? what spectrum? 15K or 20K? Also is 250watt too much for any type of coral or marine life? That is 12.5watts per gallon which could be high for some stuff but others might thrive and all stuff overtime... I have a few Zoo's now that migrate around the tank to suit their fancy *shrug*.
Sorry for being a thread ninja lbv but yours is getting more responses than mine now plus we have the exact same tanks
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#7
11/29/2005, 06:52 PM
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Quote:
If it's 24 inches deep then a 250-watt bulb would be better. My tank is also 24-inches deep and I have 250-watt MHs on it and it's fine. Of course, you'd have to use your judgement for placeing corals and you wouldn't, for example, want to place mushrooms on the very top of your rockwork. But the 250-watts, which would remember, be elevated over the tank, will enable you to keep zoanthids anywhere in the tank from top to bottom as I do, and sustain just about any coral you chose somewhere in the tank. If you'll be able to have some actinic support, then IMO, 20,000K would result in too blue a cast on the tank. It would appear somewhat dim in brightness. But, remember too, that it's a matter of taste when it comes to that. I have SE 14,000Ks with blue supplementation from PCs and I like the color rendition of that lighting. If you use VHO for actinics, they're very efficient for that purpose and I have seen that some people use 10,000ks with the VHOs and find that very good. But, if you have actinics, I'd think that you'll be happy with either 14,000Ks or 10,000Ks. I don't know how blue the DE 15,000Ks are so I can't help you there. I would suppose that it's similar to the 14,000Ks but I don't know for sure and maybe someone else with experience with those will post.
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Most people get results...I seem to have consequences |
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#8
11/30/2005, 09:30 AM
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Thanks... I am not entirely found of the blue I just like the color it brings out. I would like to go for just clarity of the light. Pure light if you will which sounds more like 14Ks which gives a small hue of blue to bring out the natural colors of the corals. I would like to keep Zoos in there so I will probably go with a 250watt and make a canopy that will hold it with a couple fans for cooling.
Only concern I would have then with the canopy is trapping in heat and putting the lamp pretty close to the water. Will MH spread out enough in the tank only being proably at max 6in off the water? A 20H is just a 10g though not a lot of surface area in the opening.
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Why do I always like the expensive hobbies? |
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#10
11/30/2005, 01:51 PM
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Quote:
If you are going to go with a closed canopy instead of suspending a pendant, you will have to be particularly careful about venting. You're right about the relatively small surface area on the tank and its consequent limitation on oxygen exchange (which would be further taxed by potential heat which reduces oxygen saturation and) which is so important to marine fish. Some, like Anthias are very sensitive to insufficient oxygen so you might want to stay away from them altogether. So, you'll have to address the heat issue and the oxygen issue adequately for your configuration. I would have a fan on each side of the canopy, each going in the same direction. Don't for a moment doubt that two will be more efficient than one, even in a rather short canopy as yours will be. You mentioned that you will have a 10-gallon sump and I think that it's critical that you do have a sump if you're going to have a canopy on that tank. The sump will enable you to have the evaporation that you mentioned and also you should have the best protein skimmer you can running on it 24/7. That should give you adequate oxygenation to make up for the small surface of your reeftank, as well as the potential heat transfer into the water-column from the lights in a canopy. Quote:
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Most people get results...I seem to have consequences |
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#11
11/30/2005, 02:02 PM
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Yeah, I have opened up a can or worms with the sump. I have an old 10g tank that I can convert into one with a small fuge in it also. I have plent of LR rubble left over from my shipment for the main tank. I would like to make one though as it will give me good experience for the 120 project that will probably start up in March if I can find that leak in my bank account and patch it up...
On a tank that size I would imagine that a hang on U-tube will work well enough for a over flow and I can get rid of all my hang on stuff (skimmer and phosban reactor) and be able to add more stuff. Any suggestions on how to return the water back up or how much flow I need back and forth? Anyone have any Cheato they want to send me or anyone in the Raleigh, NC area that wants to come over and help with the design and implementation The skimmer will run 24/7 on the sump though it is a hang on the back kind and a poor choice but it was a whim as my early stages of the tank were going downhill fast and it took me 3 weeks to realize I had to let the bubbles run until it broke in Seaclone run, Seaclone bubble, Seaclone up to 80gallons barely sufficient enough for a 20gH
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Why do I always like the expensive hobbies? |
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#12
11/30/2005, 03:22 PM
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Quote:
Quote:
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Most people get results...I seem to have consequences |
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#13
11/30/2005, 04:49 PM
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Re: Switching from PC to Metal Halide / VHO question
Quote:
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