# T5 HO Light Postitioning



## Forgotten Path (Apr 3, 2009)

I am currently setting up a 46 gallon bow-front NPT with Current USA's Nova Extreme Freshwater fixture... And I have encountered a problem.

When using the legs that come with the light fixture, it seems like there is not much light entering the aquarium. When you take the legs off and set the fixture on the canopy, the light entering the aquarium is greatly improved. I can only surmise that most of the light is bouncing off the glass canopy when using the legs.

However, at room temperature (about 70-72 F, not my planned 76 F) there is quite a bit of condensation on the canopy, which I am also concerned about scattering light, and I am sure once I get the heater in there will be even more...

I would like to use the light most efficiently (I can already feel the power bill going up), so here is the question:

Should I remove the canopy and use the legs to suspend the light over the tank? The fixture says not for use over open water, but it will clear the water by at least 4 inches, and there will be little or no disturbance on the surface (internal Fluval), and the fixture has a "splash" guard over the bulbs. This would also allow emergent growth.

Or, should I leave the canopy on and set the fixture on it, and find some means of dealing with the condensation (like taking the plastic strip off the canopy <-would that even work)?

I don't want to do anything unsafe or dangerous (putting the fixture over water), but I would also like to have an easy solution (like getting rid of the canopy), so I can't decide which would be best...


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## vancat (Nov 5, 2004)

I would say either don't use the glass, or put the light down on the canopy. I can tell you that I used a fixture on top of a glass canopy for years.... and next time I am going with no glass & legs.


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## bosmahe1 (May 14, 2005)

I use a 46 gallon bowfront with a Current Nova Extreme 4x39 watt T5HO lamp. I mounted the lights on the legs and took the glass lid off. The condensation does indeed block a lot of light. I did notice improved plant growth with the lid removed. The disadvantage is without the lid, there is increased evaporation and heat loss in the winter. The evaporation does remind me to do my weekly water changes which is a good thing but, I can imagine my electric bill suffers a bit in the winter.


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## bosmahe1 (May 14, 2005)

Additional comment:

I don't have any condensation or water spots on the light fixture without using the glass tank lid.


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## vancat (Nov 5, 2004)

I also found that the glass gets "etched" over time and also cuts down on light. 

Those glass tops (especially bowfronts) are dang expensive, too. I paid $90 for a 72 bf replacement glass top. Ouch!


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## bosmahe1 (May 14, 2005)

My glass top had the black plastic hinge in an inconvenient position light wise, so I looked at a replacement top from a different manufacturer and the LFS wanted $45.00 so, ouch is right.


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## Zapins (Jul 28, 2004)

You can certainly use the light on top of the glass canopy. The condensation is temporary. Once the light has been on for a while it will heat the glass up and evaporate the water on the other side (turning it clear).

Also, by adding a heater to the tank you will be reducing the condensation because condensation is caused by a difference of temperature. If the tank's temperature is warmer there is less of a difference in temperature between the hot glass (with light on top) and the warm water, so less condensation forms.

As for the calcium build up on glass, what you can do to remove this is simply grab a few kitchen paper towels and place them on top of the glass on a counter (as flush with the glass as possible), then pour some white vinegar onto the paper and let it sit for 20 minutes or more. Then rinse off the vinegar and your glass will be clear as the day it came. The vinegar is slightly acidic and will dissolve the basic calcium off the glass. The paper towels keep the vinegar evenly spread over the glass and help to stop it from evaporating while you wait for it to clean the glass. 

I'd also like to mention that people have tested how much light gets through glass that has a lot of calcium buildup on it, and it barely affects how much light gets into the tank, so don't worry too much about light loss due to glass scum.


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## bosmahe1 (May 14, 2005)

Zapins,

I used to use vinegar on the glass and it worked well but, the idea of pouring it on the paper towels is cool idea. Thanks.


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## vancat (Nov 5, 2004)

If you let it build up too long, it does not come off anymore, even with vinegar. The glass itself becomes etched. There was a thread on this somewhere here before.


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## Zapins (Jul 28, 2004)

bosmahe1 - thanks 

Yeah... it does seem to get etched over time.


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## Forgotten Path (Apr 3, 2009)

Sorry for my non-responsiveness, I went on vacation shortly after posting...

Currently I am trying it without the glass canopy (on the legs), and the evaporation doesn't seem to bad, maybe an inch a week at room temperature...

Zapins, I'm not sure that my two T5's will get hot enough for evaporation to clear the glass... Of course, I'm not sure if I've ever had it on long enough to find out... If the evaporation is too much of a pain, I will go with that approach, and hope it does get warm enough (or warm enough fast enough not to cut in on a lot of light time). I'm going to stick with the above approach for now, since I like the idea of emergent growth, and since bosmahe1 has never had any problems using his fixture in this manner. I will keep in mind the cleaning techniques for my other tanks, especially my African clawed frog tank, since it has a ton of hard water build-up. Thanks!

Thanks to everyone for their input!!


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