Poll: Metal halides - Pendant or Hood w/ questions

[Mark B]

I am in the process of planning a set up for a 29G seagrass tank. After some deliberations, have decided to go with MH in either 400W or 250W leaning towards the 400W. Considering using pendants to help disipate some of the heat from the halides.

Poll: Are you using halides in a hood or a pendant (especially on smaller reef tanks 55G or less)?

Questions

Hoods
1) Do you have heat problems?
2) How many fans do you use? Are they blowing in/out/both?
3) Do you use a chiller?

Pendants
1) Do you have heat problems?
2) Does your set up include fans in the pendant?
3) Do you use a chiller?
4) Are the bulbs mounted vertical or horizontal?

Thanks for the replies,

Mark

[jimmy n]

Hood type: enclosed with open back, two side vents

Lights~: 3 400 watt MH and two vhos

Fans: 3 blowing in

Chiller: no

Temp: 80-84 degrees



Not the tank size you were looking for, but hope this helps anyway.

Jim

[dendronepthya]

I have used both in he past and am currently using pendants. The pendants I am currently using are CSL Prism Pendants(horizontal). They are 400W, and come with a 3" fan. I don't like the sound of 3" fans so I turned the fans off. The noise was much better, but it led to a dangerous situation where one of the MH bulbs was severely warped and nearly exploded. I am now in the process of replacing the 3" fans with 4' fans since the larger fans are much more quiet. If you are going for 400W halides, pay more attention to disapating the heat around the bulb rather than the heat over the tank. True, the bulbs heat the water, and you do have to account for that, but first worry about the bulb's likliness to explode and cause a fire. Chances are, if you are getting enough air circulation to the bulbs, you won't have to worry so much about the effect on the tank's temperature.

[Mark B]

dendronepthya,

Thanks. I hadn't considered using fans to disipate the heat around the bulbs. Was more worried about the temp in the aquarium rising too high.

I looked at your web site. Saw that you were using the pendants resting on top of your canopy. That would be a good option for me as I already have a canopy. The canopy is too low to use for MH, but I could cut a hole in the top to have a setup similar to yours. If I decide to go with a hood, I would have to build/buy a new hood to use MH. Your tank gives me another option to look at.

Mark

[Doug]

Hi Mark,

I have a setup that uses pendants which sit on top of a board that is attached to an All Glass pine canopy. It is on my 90g but the setup should be simular to what you are talking about and somewhat like Dendros'.

Here is a link to some pictures that I took a while back.

MH pendant hood (http://38.222.244.200/dougw/MHlights072400.htm
)

I have two fans blowing into the hood from the back that come on with the lights and I have a third fan on the top which I have never needed to turn on yet. I cannot keep my tank much over 79 degrees without the heater coming on all the time. There are 2-250w Iwasaki MH's and 2-110w VHO's. One thing that I think that helps me keep the heat down is that I use the glass tops on my tank and they seem to act as a barrier to keep the heat out. I also keep my house under 70 degrees all year around so that might be helping me also.

HTH

Doug

[dendronepthya]

My setup was a result of not having permission to hang the pendants. I would have liked to have them hanging to help disappate the heat, but the setup I have right now is working pretty well.

The water temperature of my tank hovers around 80 degrees in the winter,a nd about 82-84 in the summer. Ideally, I would like it to be a little cooler. I think when I add in the new 4" fans, my heating problems will be solved.

I am very partial to pendants because they are very flexible as far as applications go. In your case, you can get a good quality pendant now, and if you decide to upgrade to a larger tank, all you would have to do is add another rather than buying a whole new lighting setup. If you then want to move up to an even larger tank, you just add another.

There are some things to consider about lighting a tank that small with 400w halides. Temperature is definately an issue as is the chance of burning your animals. You really can't acclimate new arrivals easily, and I have noticed that some corals react very poorly to huge amounts of light early on. In a seagrass tank, you're looking at LPS corals and the such, and many of them(elegance, etc.) do not need extremely strong light and would likely do better in a lower light environment. Something to think about anyway.

[Sea Dragon]

Someone asked me about the lighting on my 29G recently and here's what I wrote back:

"It's a (250watt)6500K iwasaki mounted in a spiderlight reflector. The ballast is a PFO. I mounted the reflector into a 11x13 inch wood box made out of pine and hung it over the tank with four chains. The bulb itself is 8" above the waterline and I'm not using a fan. Without a fan the reflector gets too hot to touch for more than a few seconds, but the rest of the enclosure just gets warm.

The light does warm up the tank a bit. It's hard to say how much because the temperature of the room is 72 degrees and I have the heater set to 78. The heater runs a lot more at night than during the day. The heater does run sometimes during the day though, so I know light doesn't warm the tank more than 6 degrees. Overall I'm happy with it and was actually expecting it to be much hotter than it was. It only gets about as hot as a 75 watt incandescent, which of course can get very hot in a closed enclosure but cools nicely in a pendant."

Btw, I'm not using a chiller and the bulb is mounted horizontally.

[Mark B]

Dendro, I'm single, so I don't need to get permission to hang pendants. Hopefully that won't change in the future ["But honey, the lights are better for the corals where they are."]

I eventually want to have a bigger tank, so my thinking is that a 400W halide will work on the tank I am planning and any future tanks.

I am planning to have a shelf on the wall behind the tank with a skirt to hide the equipment if I use a pendant. If I make it a little wider and cover part (2 inches or so?) of the tank, I can create a slightly shaded area at the back to place some of the more light sensitive corals. I am not sure if I will include elegance corals because of their current problems, but it will give me an area to acclimate corals. I could also place an actinic and maybe a moonlight in the overhang part.

I am also planning to use chains to hang the lights. That way I can use S-hooks to raise the lights up a couple of inches as needed.

Mark

[Edited by Mark B on 12-25-2000 at 06:19 PM]

[olgakurt]

I have a 175watt 10k German MH on a 20g high tank. I built the light enclosure so it could be either a pendant or enclosed hood-the bulb is horizontal.


Right now it is suspended off the tank w/out a fan. Light at about 6-8" from water. No heat problems.

I am planning to add one fan and lower the light to be a hood so I can buy some known "carpet surfers" without having to worry too much.

I haven't had any problems with heat w/out the fan in a somewhat pendant style, but more worried about adding fish.