Thinking about upgrading to MH lighting

[JGard]

I have a 20H and I'm currently running the 2x65W PC, one 10k and one actinic.

However, I'd like to start keeping clams. I think they're absolutely gorgeous. So, with all the OT I'm doing this month (stupid Chicago trials), I'm going to have lots of extra cash, so I was thinking of going MH.

Ideally, I'd like to get a hanging pendant. Right now I keep my tank at about 81-82 degrees, because the PC lights heat up the water to that temp...so if I tried to keep it lower, it would fluctuate each day and night, and I didn't want to stress my fish/coral with that.

So if I went hanging pendant, I could keep it off the water a bit and therefore be able to keep my water temp at a more constant 78.

Two questions...more may come later.

First, what wattage should I get for my tank? If I wanted to hang the pendant about 8-10" over the tank, would 150W be strong enough for clams at the bottom of a 20H? Would 175W work? Is 250W too strong?

Also, I have a fully glass hood for the tank. Is it OK to have that on there with a pendant hanging that far up? I have a purple firefish and from what I've read, they're jumpers...so I need to keep my tank covered at all times.

Thanks for all your help.

 

[G.T]

150 or 175 would be fine. It is a step forward but you may have a surprise with the heat factor, you state that because it is kept a few inches from the surface that it will be ok. You may be surprised and may have to place a fan on the unit to keep things running to temp.

 

[MikeG]

Also if you are having heat issues with pc's not being able to keep a steady temp under 80, you may want to look into egg crate to keep the fish in and remove the glass top. Evaporative cooling will help a lot with the temp. You will also get much better gas exchange.

 

[JGard]

I've heard of an egg crate before, but I don't really know what they are. I'll check google for that.

As for heat...even with a 175W hanging a few inches up, it'll still heat the water, huh? Doh! Well, the temp isn't the main reason for this...it's more for being able to keep cooler lifeforms in my tank.

Oh, and Mike, I've got a nice refractometer being delivered this week Your PM from last week scared me! heh


edit: Checked out egg crates through Google. Now I know what they are. OK, those would be a good idea. I think it would help quite a bit with the heat...but I also think the tank would suffer from a lot more evaporation than it already does.

 

[MikeG]

Can get egg crate at HD in the lighting department or with the ceiling tiles. The evaporation would be higher and you would need to top off more often.

I also agree, you will probably have more temp issues going with MH. Just something to keep in mind.

Glad to hear that you got a refractometer. Much more accurate than the swing arm, good investment!

 

[Troubleman]

eggcrate is in the lighting section of home depot....used for commercial flourescent lights. as far as heat goes, if the pendant is hanging in the open above the tank it will heat the water slightly during the day, not nearly as much if the mh light was in a hood....I don't see why you would need a fan blowing on it.

bob

 

[JGard]

Cool, thanks. I'll hit Home Depot this weekend.

This is the light I'm contemplating...any yays or nays?
http://www.hellolights.com/17penfix.html

I plan on attaching it to the ceiling. I'm guessing they're fairly light, so a regular ceiling/wall hook or something of that sort should be sufficient. And if I should go w/ 15k or 20k bulb? I'm not planning on running a supplemental actinic.

 

[Troubleman]

Make sure you attach to something sturdy.....You wouldn't want this fixture to accidently fall into tank....looks like a nice lite by the way.

 

[JGard]

Thanks. Just put the order in. I'm excited.