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OK, I sprung for the MVB so I now have full spectrum lighting coming from the basking lamp, in addition to from a florescent. I bought a 100 watt T-Rex flood and set it up the minimum 12 inches from the platform, replacing a regular Repti Spot bulb. Wow, it was expensive!

Anyway, all is well, except that the ambient air temperature is lower, I suppose because the MVB does not throw off as much heat as the old incandescent. It was about 90 under the old lamp on the platform; now it is about 80, give or take a few degrees. Is this an issue?

That's not warm enough at all. Maybe move the lamp closer. I use the same bulbs and I can't say I keep them a foot away. Does it say why it's a minimum of 12in?

Yes, the directions with the new mercury vapor bulb (MVB) say a minimum of 12 inches from the basking platform. Do you think I need to add another lamp for heat?

How odd! I've got the exact same bulb. It's positioned right now at 14" from the platform (the platform rises and falls a couple of inches as water evaporates and is replaced). I just put the meter on it and it seemed to stabilize at 93 degrees. The MVB should be a very hot bulb (though I'm not sure how it compares to a standard incandescent). I certainly wouldn't put it closer than 12" because of the risk of explosion if water splashes on it.

I used to have a Powersun 100 watt MVB. I had to keep it 12" from the platform to motivate Spot to bask but I worried that it was too close to the water so traded it out for the T-Rex, which more powerful and I can keep it further from the water. Spot basks real well with this bulb.

I wonder if you're getting a false reading. What kind of thermometer do you have? Could you check it again and make sure it stays up there long enough to stabilize?

How you position your probe is important. Here's a thread on the subject:

http://redearslider.com/forum/viewtopic ... ht=digital

I agree with Spotsmama.....it's odd that your T-rex bulb is not providing enough heat (especially since the T-rex is supposed to be the most powerful MVB out there). I have the 100W Powersun (weaker than the T-Rex) and Sheba LOVES it. She basks daily for hours & I keep it a minimum of 12 inches from her basking spot (that translates to roughly 10" from the top of her shell). I have touched Sheba on the top of her shell while she is basking to make sure she is not too hot up there. She always feels nice & toasty (comfortably warm), but not burning hot.

You may want to check the thermometer you are using because 80 degrees doesn't sound right. Hope that helps.

When I used a 100-watt T-Rex flood MVB, I had to have it 14 inches from the platform before my turtle would bask, and at that distance the temp was 88F. (I'd follow the mfgrs instructions and not have it less than 12 inches away.)

Did you buy a spot or flood? Do you have the light hanging over the basking area or clamped (hanging is better). Are you using a dome reflector with the bulb (it will help concentrate the heat downward)?

I'd recheck the temp with a thermometer. Put it where the turtle basks (you could put the thermometer on a rock/object that's roughly the height of the turtle's shell to get a more accurate reading). Leave it under the light for 20-30 min and check the temp. I use a regular thermometer that I know works to check the temp, not one with a probe, and I test a few times just to be sure.

I just got a 100watt T-Rex flood too and had the same problem! With it about 13-14" away from the platform and it only got to about 81 degrees. I felt so ripped off! But I got clever and put a back ground on the outside of the glass (my basking area is in the corner of the short side) and then insulated it more with an old, clean bandana.

It's safely up to 90 degrees now. I was worried when I first purchased it because everyone on here suggests it only being used for 55 gallon tanks or larger and I have a 30 gallon. But when i hooked it up I was sooooooo mad!

Try some insulation on the outside of the glass: cloth, cardboard, etc.

Perhaps a reflective dome lamp will affect the temperature as opposed to a non-feflective dome lamp?

Cayte923 and LKitch, what kind of fixture do you have - clamp or hanging?

I have a background behind the basking dock and probably 10" of the distance above the tank is wall and 4" is air. I don't have a reflector fixture, though the back of the bulb is silver.



With this setup and a T-Rex 100 watt MVB flood bulb I get a lot 93 degrees on the basking area, measured with a digital thermometer.

OK, I think it's better now. I tried a second thermometer and kept it there 15 minutes to be sure of my reading and it is 90 degrees. So maybe my first reading was off. I lowered the fixture a bit. I already had a reflector on it, though I'm not sure that makes much difference, given how the bulb is constructed---it's a flood. I use a clamp, but because it is affixed to a vertical wall above the platform, it shines straight down as if it were hanging. Finally, I just saw my turtles basking under the new lamp, so I guess it's OK by them! Would love to post a pic of my set-up---how is that done?[/url]

I'd love to see your setup! Here's how to post:

http://www.redearslider.com/forum/viewtopic.php?t=1811

I have mine in a reflective clamp but it is clamped to a shelf about 6" above the tank so the bulb is in "hanging" position. When I first turned on the lamp yesterday I waited for an hour for it to heat and used 2 different thermometers. Maybe it's my bulb? Near the base metal coil does anyones have a bend in the glass? Maybe that the problem. It's alright for now. Unfortunately I got it from ReptileDirect.com and am having problems with them...( http://www.redearslider.com/forum/viewtopic.php?t=8242) So I can't really return it to them.

OK. Here is a photo of my set-up. Please note this was taken before I replaced the old bulb with the MVB.

http://www.flickr.com/photos/88443969@N00/423571826/

There's a little bend in the glass on my bulb - don't know if it's the same as what you're talking about.

I said my bulb was 4" above the wall of the tank but that's not right - it's more like 3". Maybe since yours is 6" above the tank wall (I assume that's what you're saying) more of the heat dissipates before it reaches the platform.

Nice indoor pool, LKitsch. Are you using the same dome fixture with the MVB as you did with the regular basking light? The one I see looks a little small (unless it's the pic). Since mercury vapor bulbs give off a lot of heat, if it is a small dome, using a larger one would be better in that it would trap less heat (you may find that the bulb overheats more frequently with a smaller dome).

BTW, how are your rescues doing?

adam85491, if by reflective dome you mean that the inside of the dome is silver/aluminum vs. one that isn't (and is therefore non-reflective), both will help concentrate the heat, but the silver-lined dome will increase the amount of UVB rays your turtle gets.