anyone had this problem with halides?

[reefman23]

I came across a post while researching for my mh retro. Firstly, i plan on designing a 20"L x 6"H hanging canopy very similar to this one, except that the back will be open, and note that there is ventilation along the top ----> http://www.thekrib.com/Lights/Lobos/ . I will be putting a 70 watt halide along with 2 x 40 watt PC's. i planned on using two of the evercool 80 mm fans on this link ----> http://buyextras.com/b80dc12vbabe.html .

First question: Is this too much air flow? Should i use only one? two smaller fans?
Second question: Back to the post I came across ---->http://www.reefcentral.com/forums/showthread.php?s=&threadid=30751 ,has anyone had a problem with running their bulbs TOO cool, ie. yellowing of the light, etc?

 

[sadielynn]

First question: Is this too much air flow? Should i use only one? two smaller fans?
Second question: Back to the post I came across ---->http://www.reefcentral.com/forums/showthread.php?s=&threadid=30751 ,has anyone had a problem with running their bulbs TOO cool, ie. yellowing of the light, etc?

Wow that will be a nice hood. As for running the fan I would use the 2 smaller fans , I have never heard of the fans cooling the light so much that it would yellow out.... if that is what you are asking .We have 4 fans on or 72 wat pc light and you can touch the bulbs with out burning your hand , even if they have been on all day ...the tank temps are stable with a heater at 75.5-77.7 degrees it usually doesnt go any higher than that or lower.... I just dont think that you can have to many fans on the lights just my .02

 

[reefman23]

i agree with you, sadielynn, i think im going to go with two smaller fans. but when i read that post about people who have added a fan or two to their halide setup, and then immediatly noticed the light yellowing, i became a little concerned. However, i read the whole post and it seemed to me to be a problem mainly with the higher wattage SE lamps and only when the air was directed AT the bulb. this makes sense, though, when you think about it like this: If you heat up a sheet of metal until it is glowing orange, it is that color because of the temp that it is heated to. once you change that temp by lowering or raising it, that color will change. Is there an ideal temp that these mh, specifically DE, should run at? or the cooler the better?

also, i am going to be doing a journal on my mh retro, beginning these next few days. I plan on starting construction by this weekend, and i should receive my mh 70 watt retro kit by then. plenty of pics and questions to come!

 

[skipm]

With such an open canopy design I think that you would do fine without the fans at all. I used to run MHs on my 75 and you could place you hand on the reflector directly over the bulbs and it would barely be warm. As long as the fans are just making air circulate within the canopy and not blowing on the MH I don't think you will have any problem. HTH, SKip