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	Metal Halides -- overkill?
SpecialK Big Fish Posts: 365 Kudos: 116 Votes: 3 Registered: 18-Jun-2003	Hi all - question about lighting for a planted tank (project is just in the "design" phase). Is metal Halide lighing overkill for freshwater planted tanks? I have a 75-gallon and an available 2x150 watt MH with 55W Actinic. That would be 300 watts of some pretty high intensity lighting, not counting the actinic. I have a general knowledge of the watts-per-gallon "rule of thumb", but does it ever become overkill? And if I could use the MH, what spectrum bulbs would I want? I have 10K now. Thanks!
Posted 26-Jan-2006 11:43
Sonic2041 Enthusiast Posts: 152 Kudos: 142 Votes: 19 Registered: 19-Dec-2004	if you already have the fixture you can use it. 300 watts would put you ate 4 wpg. i would not use the actinics though. they would make it look funny. 10000k would be fine for plants but if you buy them you could go a little lower. the only thing i would worry about is if you don't keep everthing balanced you will have major algae problems. if you have to buy the fixture i would go with something else.
Posted 26-Jan-2006 11:43
Megil TelZeke Fish Addict Posts: 863 Kudos: 890 Votes: 393 Registered: 21-Jul-2003	oof definetly overkill i'd say, they get way hot O.o and their temperature isn't really right for plants. 10K is good for corals and the like. 6700K is better for plants. I do no think they make MH of that temperature. another thing to note is that Mh are more of spotlighting than overall tank lighting, they are very much like incandescent in that sense since they have a smaller focal point than flourescents. Last edited by Megil Tel'Zeke at 17-Oct-2005 22:57
Posted 26-Jan-2006 11:43
SpecialK Big Fish Posts: 365 Kudos: 116 Votes: 3 Registered: 18-Jun-2003	I'm not so worried about the temperature since the MH would be elevated about 8-10 inches above the tank, plus the fixture has a fan. When using it over my saltwater tank, I never had any problem with raised water temperature. I believe that MH bulbs do come in lower K ratings - I know Aqualine sells a 5K, and I thought Coralife had something a little higher. I don't know. I'll have to keep investigating and see what some other folks come back with.
Posted 26-Jan-2006 11:43
bensaf Fish Master Posts: 1978 Kudos: 1315 Registered: 08-Apr-2004	Definately overkill. You'd really really need Co2 supplementation with those lights otherwise you'll end up looking at pea soup water. If you can't or don't want to go with the Co2 I'd stick to one 150 watt MH. 10,000k will cut it, but if you can get a 6700k bulb better again. If you're intending to add Co2 I'd still stick with one MH and the 55watt, but dump the actinic bulb. More light, even with Co2 injection, the more of a tightrope and balancing act everything becomes. Zero room for mistakes. More work too. Some days you're the pigeon and some days you're the statue. Remember that age and treachery will always triumph over youth and ability.
Posted 26-Jan-2006 11:43
LITTLE_FISH *** Little Fish *** Master of Something Posts: 7303 Kudos: 1997 Votes: 670 Registered: 20-May-2005	I cannot say anything else than what has been said by Megil and Bensaf already. Overkill! I “only” have 3 wpg and that is more than enough, as can be seen in [link=This Link]http://www.fishprofiles.com/files/forums/Planted%20Aquaria/64425.html?200510180911" style="COLOR: #ff6633[/link]. Ingo Proud Member of the New Jersey Aquatic Gardeners Club
Posted 26-Jan-2006 11:43
SpecialK Big Fish Posts: 365 Kudos: 116 Votes: 3 Registered: 18-Jun-2003	Thank you to all for replies! I've dabbled with FW planted tanks, but on a very small scale where a simple compact flourescent spiral bulb was sufficient. I had great success, but a 10-gallon US is very different from a 75-gallon US. The good news is, I think I'll be able to get a pretty fair price if I sell my existing MH fixture used. So I can use that toward a more appropriate fixture. Thanks for explaining that the MH would create zero margin for error. That's definitely something I need to take into consideration since I'm e to error as I go about this process.
Posted 26-Jan-2006 11:43


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