uv radiation

[shabreeson]

I am building my own lighting system frame and all, and to fit the MH into the frame I am actually separating it from its frame that came with it. which means that I am not going to use the tempered glass that came with it.

do I need to get a special piece of glass to protect my fish and corals from the uv radiation or would it be ok to use regular glass?

also how much will the 250w MH lighting heat up the tank if the light is 3-3.5 inches from the water level?

please answer both questions, and in order if possible.

 

[kgross]

Does your MH setup use mogal socket bulbs or HQI double ended bulbs? If they are mogal socket, there is not very much UV, and a UV shield is not needed. If they are double ended a UV shield is needed and normal float glass will work fine as long as it is at least a couple inches away.

How much heat, well that is very hard to say, depends on the size of the tank and the amount of airflow. It will put out quite a bit of heat, it is just very hard to say how much it will heat up the water.

Kim

 

[shabreeson]

It's a mogal socket and it is a 55 gallon,I'll have one small fan built into the frame

 

[madadi]

the mogul type bulbs have a UV shield built into the outer glass of the bulb. HQI dont have it but your fine with a mogul type bulb. just have it high enough so not much water can spray on the bulb.

 

[hllywd]

My two SE 250s are about 6" off the water with no glass, they will take some substantial splashing and not break if you're worried about that. Personally I'd have them closer if it wasn't for heat and access issues.

Heat was a minor problem last summer, it's a 120 and daily the temp would creep 2 - 4 degrees even with the AC running. I'm considering a chiller or at the very least a room AC to help out the central unit which is a little undersized for our house anyway, everything is fairly new but the previous owners were low bid people...

Tim

 

[shabreeson]

well there is minimal splashing with my tank and even so I was planning on putting some ordinary glass in the frame and cut plexiglass to fit my tank top in order to prevent evaporation,my only concern is that it will reflect too much light

 

[Fiziksgeek]

I would stay away from the glass shield if possible, it cuts down on the amount of light getting to your tank. And a second layer of acrylic (plexiglass) would do the same also, not to mention the fact that it will heat up and likely distort, maybe even crack!

If you really want to have a solid top on the tank, I would recommend a single layer of glass, and skip the shield on the MH.

 

[rustybucket145]

3" is WAY too close to the water. It's gonna cook your tank. ESPECAILLY if you use glass covers. I'd HIGHLY suggest NOT using the glass covers and raising the bulbs 6"-8" minimum over your tank. 10"-12" would be optimal with a good reflector.

Evaporation is your tanks natural defense against overheating (kinda like a person sweating) What happens when you block a person from sweating? They overheat! This will also happen to your tank.

You WANT evaporation to happen, stopping it is... well.... just CRAZY!!

 

[shabreeson]

easy, it's ok, I'm listening to what you are saying ... I think I will just put a piece of glass in the frame,I won't stop the evaporation of the tank, that makes sense.

shouldn't the piece of glass in the frame help stop the heat from reaching the water??

I'm not so much concerned with how much light is entering the tank as I am with the possibility of overheating.

 

[shabreeson]

bump

 

[hllywd]

I'm concerned about the light I'm paying to produce. Personally I'd rather not waste it on a glass shield I've proven to myself is unneeded. Even clean window glass blocks a lot of that energy!

Tim

 

[kgross]

If your not worried about the amount of light going into the tank, just heat. Just don't turn the lights on. That way no heat will be produced.

 

[shabreeson]

all that I was saying was that I was planning on having more than enough light,and the light will be close to the water surface, so that I could have a heat shield without much depletion on light.

ok so how much would having a piece of glass, only as long as the MH bulb, block the light?

 

[Pbrown3701]

I would use the glass shield and put the lights close to the water (mine sit about 2-3 inches away). But if you do this, add another fan to circulate air over the water surface and DO NOT put a cover over the tank. You will rely on evaporative cooling to keep the temp down...

I have 4 4" fans blowing over 2 250W MHs on my 75gal. I evaporate about 3-4 gal a day but my temp won't creep too much over 83 - compared to about 80 without the Halides on.

 

[shabreeson]

thanks for the help