MH Lighting Question

[jimsha]

I have a 90 gallon RR tank inside a cherry wood Mission Classic stand with canopy. I would like to have MH lighting with some PC or VHO. I was wondering what the minimum height is for mounting the MH lighting?

[akrimmel]

depends on what you plan to keep, you can go as high as one foot down to 6 inches give or take the wattage light you plan to use.

[jimsha]

What do you recommend for this size tank AKRIMMEL? I would like to keep a little variety of things...(ex. Clams)

[akrimmel]

with a 90 dual 175's as the 250's will give off more heat or the best thing going IMO T5'S 6-8 lamp personal choice.

[bertoni]

What are the dimensions of the tank?

[akrimmel]

if he has a standard 90 should be 48 length like a 75 but taller, thats where he might need the stronger lighting due to the depth

[jimsha]

its 48x18x24

[akrimmel]

i stick to my first post as that is what i would consider with a 90

[jimsha]

thank you ... so dual 175 ....what about some actinics?

[akrimmel]

go with 14k's and you wont need actinics, but like i said could do t'5 as well since you may have a heat issue in FL.

[jimsha]

ok...so the MH 175's is ok to be only 6" from the water? Sorry about asking so many questions...just dont want to make any more mistakes.

[MarkD40]

I recently added 2 X 250 watt MH hanging over my tank 6" above the water and I have seen no increase in temperature. I previously had an enclosed hood with 6 X 96 watt PC's.

I absolutely LOVE the MH lighting. I have done a lot of snorkeling in the Caribbean and the ripple effect of the MH's makes my reef look so natural I feel like I am looking through my goggles. It is basically like taking a cheap vacation every day. Well........ not really but it sure looks nice.

[akrimmel]

is possible but just dont drop it down to 6 adjust slowly, now that being said that close to the water surface it will heat the tank more so than usual, i would average the height between 8-10 inches as that would be more acceptable. unless you have any corals high in the tank this could bleach them, if the majority is down towards the bottom you could go lower with the MH. when ever you introduce MH as new lighting dont keep them on as long as what the other lighting was in for and increase time over weeks as well as when you move the light up and down gradual as to acclimate your tank to the changes slowly.

[akrimmel]

MarkD40
as you have a bigger tank than jimsha the heat might not be as noticeable as well as the contents of the LR and LS to absorb some of the heat as well.

[bertoni]

If you pick a high-efficiency bulb and good reflectors, I suspect 175 W will be okay. Some people would prefer 250 W, which is what I chose for my 75g.

[akrimmel]

agreed bertoni is is just that this is a loaded topic with so many variations.

[MarkD40]

My tank is only 6" taller than his, but I do have a 75 gallon sump and a separate 20 gallon refugium for a total of maybe 150 gallons circulating, so point taken.

I assumed the MH's would increase the temperature of my tank and this is the reason I waited so long to make the change. I did not want to get a chiller! I was pleasently surprised when I noted no increase in temperature. I now wish I had gotten 400 watt MH's though the 250's seem to be enough light with 2 96watt actinics.

[akrimmel]

yes as you know the more water to dissapate the heat the better when it comes to MH'S.

[jimsha]

How much would my temp. rise by using MH lighting? Currently my tank runs at around 78? Sounds like I'm gonna need a chilller huh? Especially since I have a canopy and can only spare about 6" taking into account that the lighting will probably take up 3" out of a total inside measurement of 9 3/4"(measuring from the inside top of the canopy to the water)

[MarkD40]

Jimsha,
Hard to predict, but if you hang the lamps above the tank with no canopy you will minimize heat transfer. I had the same concern as you but it worked out fine. Love the MH's!

[jimsha]

Thanks for the quick reply Mark, but the wife will not let me get rid of the canopy.

[MarkD40]

Then it may be chiller time.

[bertoni]

Fans in the canopy might do the job. Worth trying, in my opinion.

[FatTony]

I have a completely enclosed canopy over my 29H that houses 175W Metal Halide, and all I had to do to prevent any temp flux was to put a fan w/vent in the back and a vent on top (to move the air in a nice cycle). No chiller on my tank, and it never touches 80. I'm also a die-hard MH fan, and would recommend them to anyone.

[akrimmel]

whats up with the canopy relationship.

[jimsha]

Not sure I understand the question?