Help me out here

[Anonymous]

You have to understand, I am doing this with stuff I have laying around the basement. I have 2 - 175 watt metal halides with ballasts, bulbs, and bases.

I can't buy a new light for this little project because I am saving to buy a light for my real tank--my 55 gallon corner bow front.

so, I say lets build it and see what the heck happens

If I make nothing that works maybe I could use the thing as a humidifier or to make "SUN" Tea :lol:

 

[Anonymous]

IMO that much light is going to boil the tank regardless of how well you keep the outside cooled. As soon as something dark is added to the tank it's going to heat up from all that light energy.

I have a 250W DE over a 10 gallon and I still have to heat the water, and I don't have a fan.

 

[Anonymous]

what is the difference between a DE and a MH?

 

[Anonymous]

Oh nothing Bryan. They're both MH. DE is Double ended. SE is single ended. They require different ballasts too. You may also see DE referred to as HQI. It's basically just a more bang for your buck light. And from what I hear the bulbs have a longer useful lifespan too.

Here's what a DE fixture/bulb look like.

The fixture

The bulbs

 

[Anonymous]

Well, that simplifies my looking for a light for my main tank greatly

now I know I don't want a MH or DE or HQI light !

 

[Anonymous]

I have a 250W DE over a 10 gallon and I still have to heat the water, and I don't have a fan.

25wpg vs 70wpg...

 

[Anonymous]

or to make "SUN" Tea :lol:

:lol:

 

[Anonymous]

I have a 250W DE over a 10 gallon and I still have to heat the water, and I don't have a fan.

25wpg vs 70wpg...

Gallons don't matter!!! Distance from the light bulb, and intensity of the light do. His tank is really not getting hit with all that much light intensity compared to some people's tanks. If he puts a foot between his bulb and tank and uses a fan it he should be fine.

 

[Anonymous]

The bulb will likely be 10 inches from the tank bottom, and there will probably be a couple of pieces of glass between the light and the tank bottom.

Its still gonna be bright though...

 

[Anonymous]

I have a 250W DE over a 10 gallon and I still have to heat the water, and I don't have a fan.

25wpg vs 70wpg...

Gallons don't matter!!! Distance from the light bulb, and intensity of the light do.

If I put a 175 10" over a 2.5 gal vs putting the same 175 10" over a 250 gal you betcha gallons matter. The greater surface area of the larger tank will dissipate the heat a whole lot faster.

Why does intensity matter?

 

[Anonymous]

I have a 250W DE over a 10 gallon and I still have to heat the water, and I don't have a fan.

25wpg vs 70wpg...

Gallons don't matter!!! Distance from the light bulb, and intensity of the light do.

If I put a 175 10" over a 2.5 gal vs putting the same 175 10" over a 250 gal you betcha gallons matter. The greater surface area of the larger tank will dissipate the heat a whole lot faster.

Why does intensity matter?

But no one puts a single 175 over a 250 Guy. They put several of them over it, and the heat is more difficult to dissipate because of the lower surface area/volume ratio in a larger tank. This is why large tanks sometimes need chillers but nanos rarely do. We can get away with enough cooling from evaporation alone. If anything the small size of his tank is a benefit. It will be very easy to cool with just a fan.

Intensity matters because it's the best way to express what the coral is actually getting hit with. It's still just a 175 W MH. I know a local reefer with a shallow 1' deep 180 gallon tank for growing out SPS corals. 4-400W MHs. More light intensity by far, no matter where a coral is located in that tank. Yet he's got less than 10 watts per gallon, compared to Bryan's whopping 80 watts per gallon. I just think it's a unit that doesn't really reflect anything useful and is misleading at best.

 

[Anonymous]

I agree the larger tank has less surface area per gallon but that doesn't mean gallons are irrelevant, ie yes it does matter in my opinion.

We were discussing heat, not corals. The amount of light energy entering the water determines how much the water temp is raised by the light. I still don't see how intensity makes a difference.

 

[Anonymous]

Yous can disgust this all yous want to, I'm a still a buildin the darn contraption---Maw said I could if I milk the cow for a week!

:lol:

 

[Anonymous]

LOL

 

[Anonymous]

I agree the larger tank has less surface area per gallon but that doesn't mean gallons are irrelevant, ie yes it does matter in my opinion.

Do you agree it's easier to cool smaller tanks?

We were discussing heat, not corals.

Yeah, sorry for going off on a tangent. It's just the reason I have a pet peeve with the whole watts per gallon thing. For some reason people equate a 10W bulb over a 1 gallon tank to a 100W bulb over a 10 gallon tank, and it irks me. It's just not the same.

The amount of light energy entering the water determines how much the water temp is raised by the light. I still don't see how intensity makes a difference.

You just answered your own question! light energy=intensity...

 

[Anonymous]

Do you agree it's easier to cool smaller tanks?

Yep. This doesn't mean that the size of the tank in gallons is irrelevant though. A larger tank will be able to disperse energy at a faster rate because it has more surface area.

If you add the same amount of heat to a small and a larger tank the larger will not get as hot.

If you heat these two tanks to the same temp then I agree, the smaller will cool off faster and easier.

You just answered your own question! light energy=intensity...

Not quite. Light intensity has one more dimention - area.

175 watts of light from NO bulbs puts about the same amount of light energy into the water as 175 watts of MH. The MH is far more intense but each will put about the same amount of light energy into the water and heat the water relatively equally. The NO will have far fewer MicroEinsteins per M² but about the same number of total MicroEinsteins as the MH.

We're not disagreeing much here but I still believe that putting almost 3X as much light in the water per gallon as you did is going to cause heat issues. Unless, possibly, most if the light is simply reflected out of the tank.

 

[Anonymous]

I don't get how he's putting 3X as much light as I am. That's where I disagree. If you put a light meter at the bottom (top ) of his tank, 1.5' away from a 175W bulb, and a light meter at the bottom of my tank, 1.5' away from a 250W bulb, wouldn't the one in my tank give a higher reading? Virtually all of my tank is getting hit with that amount of light as well--it doesn't seem like there's anywhere to dissipate it because it's all getting heated.

 

[Anonymous]

I can imagine what Bryan's thinking right now--"screw this discussion, I'm gonna just fire it up and see what happens!"

 

[Anonymous]

LOL.... he's gonna fire it up, we're just killing time with meaningless dribble

I predict a 90F temperature 1 hour after that puppy is turned on.

 

[Anonymous]

If there is at least a foot of space, and a fan, I predict no higher than 80.

Wanna bet 100 sump bucks?