Surface area?

just information to clutter my brain with...
I saw a fomula for deciding how much wattage you need for plants...
you take the surface area x distance of light to gravel x (type of plant) divided by 11


Low light plants .08
Low to moderate .12
moderate to bright .18
birght .27

I just wanted to see what it came out as

so 785 x 19 x .12 /11= 162.7 watts of light for low to moderate light plants.

That for 72gallons is 2.25 watts per gallon

Knowledge can be deadly .....


Thanks for you help :D
 
Dude, it's 588, not 785. You have to remember that the tank isn't 18" wide all the way, only at the widest part of the tank. Thats what I took into affect when I got the average of the front and the back because they are 2 different lengths, then I times the average length by the width. I am sure that what I did is right. Also, it shouldn't be 19", it's 22" high.

So, for moderate plants, the formula should be:

588 x 22 x .12 / 11= 141.12 watts.
 
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yes 785 sounds better than 588.

hell if you just take the 48"x13" (for the shallowest part) then that's 624"^2. then you'd have to measure the circumfrence of the bow but it makes sense that its about another 150"^2.
 
Originally posted by NJ Devils Fan
Gumby, what's CAD?
Click to expand...

Computer Aided Drafting, specifically AutoCAD.

Trust me I've been earning a good living as a geometrics designer (highways, railways etc.) using AutoCAD for the past 12 years.

(I did assume the front glass is bent into a circular curve and not something more elaborate like an elipse or parabola).

Gumby7
 
Originally posted by NJ Devils Fan
Dude, it's 588, not 785.
Click to expand...


How do you get that?

a 55 gallon tanks surface area is 576. A 75's (48x18) surface area is 864.

785 sounds right to me.
 
Quick was on the right track, I don't know why I didn't think of this before, it's basic geometry. You get the area of the tank without the bow front part(12"x48") which is 576, then get the area of the bow front, which is a semicircle((pi)R squared divided by 2) which is 56.55, and add them and get 632.55.

Ergo, meaning therefore, the surface of the 72 gallon bow front tank is 632.55 inches squared. (could I sound any more like a nerd? ;))
 
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NJDevils fan; the bowfront isn't a semi circle, its smaller than that. i've no idea how to work it out but 785 sounds about right to me
 
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Originally posted by NJ Devils Fan
Quick was on the right track,
...
Click to expand...

i didn't take all those years of calc for nothing ;)
 
Originally posted by NJ Devils Fan
Quick was on the right track, I don't know why I didn't think of this before, it's basic geometry. You get the area of the tank without the bow front part(12"x48") which is 576, then get the area of the bow front, which is a semicircle((pi)R squared divided by 2) which is 56.55, and add them and get 632.55.

Ergo, meaning therefore, the surface of the 72 gallon bow front tank is 632.55 inches squared. (could I sound any more like a nerd? ;))
Click to expand...

As stated, the bow is clearly not a semi circle. Its a small slice of one side of a circle that has a radius much larger and harder to determine than from the length of the tank.

Just trust gumby and his AutoCAD, it works!
 
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