[zabak80]

I'm always thinking of ways to get the best light at the cheapest possible way. Driving home today, I thought of a weird scenario for lights over my 20g. Not that I am going to use this method, just curious as to the end result and actual wpg.

Imagine if I were to place two 48 inch shoplights, each with two 40watt bulbs over a 20 gallon, so that would be 4 40 watt bulbs for a total of 160 watts.

Now the tank is only 24 inches wide, and the shoplights are 48. So only half of the shoplights are directly over the tank. So if only half of the lights are over the tank, I am guessing only 80 of the 160 watts is actually useful.

If it was a 29 g 36 inches wide, would it only 3/4 of the light be useful?

 

[triple red]

they do make 36" shoplights...
people do use shoplights sometimes but the reflectors arn't all that good so you wont get all the wattage into the tank

 

[epicfish]

they do make 36" shoplights...
people do use shoplights sometimes but the reflectors arn't all that good so you wont get all the wattage into the tank

The reflectors are good...for what the shoplights were designed to do: distribute light within a shop.

For our purposes of trying to get as much light into the tank as possible, shoplights aren't very efficient, but people have used them before.

To the OP, if you went this route, you'd have to deal with the light spillage from the other half of the shoplight fixtures...plus, it'd look rather ugly IMO.

 

[retoid]

Id imagine it would light up half of your room alot to

 

[zabak80]

But would the light calculations be correct?

 

[epicfish]

160 watts per two shoplights.

Half of that would give ~80 watts. Re-strike, inefficient reflectors, and inefficient bulbs would give you maybe 50-60 watts of useable light.

 

[Rex Grigg]

160 watts per two shoplights.

Half of that would give ~80 watts. Re-strike, inefficient reflectors, and inefficient bulbs would give you maybe 50-60 watts of useable light.

I would actually figure more like 40 watts.

 

[zabak80]

Out of curiosity, is there any type of device available that we can put on the bottom of the tank to figure out how much light is reaching the device, then convert that to WPG?

I would love to get a definate, scientifc answer to a lot of my light questions, and something like that would solve almost everything.

 

[epicfish]

It's called a PAR meter.

First link I found. There's others for cheaper.
http://www.specmeters.com/Light_Meters/Multi-Sensor_Quantum_Light_Meter.html

 

[Wasserpest]

Yep, there are light meters that measure candelas and lux and such.

 

[epicfish]

It's called a PAR meter.

First link I found. There's others for cheaper.
http://www.specmeters.com/Light_Meters/Multi-Sensor_Quantum_Light_Meter.html

Yep, there are light meters that measure candelas and lux and such.

Out of curiosity, a PAR meter would give a better estimation of the suitability of a certain light bulb for plant growth, wouldn't it? The PAR meter will measure phosynthetically active radiation while LUX meters measure the amount of visible light per square meter.

Both would give values that can be used to compare different lighting setups, but I think the PAR meter would be a little more accurate, wouldn't it? I'm not 100% sure, so that's why I'm asking.

 

[zabak80]

Whoa! Those are expensive.

 

[Joetee]

What if you hung those 48 inch fixtures higher up? Maybe from the ceiling?
Then you would really have an open top tank.

 

[mrbelvedere]

If it was a 29 g 36 inches wide, would it only 3/4 of the light be useful?

29 gallon tanks are 30 inches wide.

Forget the shoplight. Spend your money right the first time.

 

[triple red]

What if you hung those 48 inch fixtures higher up? Maybe from the ceiling?
Then you would really have an open top tank.

if he did that ...it would make the shoplights even less effective because the reflectors disperse the light over a wide area

 

[zabak80]

What if the shoplights were enclosed within a DIY canopy and average reflectors were installed over the bulbs?

Would that limit the light dispersement?

 

[triple red]

What if the shoplights were enclosed within a DIY canopy and average reflectors were installed over the bulbs?

Would that limit the light dispersement?

yes....but now your cheap light is starting to cost you more money than it might be worth
and its still way to large (4ft) for the tank (unless you cut it down to 30")

if you are handy, i think there are much better routs to go....
but if you dont mind the looks then go for it...

 

[zabak80]

I'm not actually going to do this, just a thought I had and was curious about it. I would go the PC route anyways, just wanted to better understand the science of lighting. Thanks for the help though!