Floyd's questions about wattage

[Floyd R Turbo]

No, you still don't have it right.

A double sided 1 cube/day screen would be 3x4 and would need 12W of CFL split between both sides (6W per side)

A single sided 1 cube/day screen would be 6x4 and would need 12W of CFL all on one side. If you had 2 3x4 screens, then each screen would need 6W on one side.

Wattage stays the same.

The physical surface area of growth substrate stays the same. On a double-sided screen, you actually have 24 sq in of growth area. For a single sided screen to have the same capacity, you need to have the same growth area, but since you are only using one side, the dimensional area of the screen must double.

The reason the screen sizing guideline isn't geared around physical growth area (surface area) is that it gets confusing. It's easier to just talk about length x width and leave it at that.

[acorral]

From SM original post:

An example VERTICAL waterfall screen size is 3 X 4 inches = 12 square inches of screen (7.5 X 10 cm = 75 sq cm) with a total of 12 real watts (not equivalent) of fluorescent light for 18 hours a day. If all 12 watts are on one side, it is a 1-sided screen. If 6 watts are on each side, it is a 2-sided screen, but the total is still 12 watts for 18 hours a day. This screen size and wattage should be able to handle the following amounts of daily feeding:

1 frozen cube per day (2-sided screen), or
1/2 frozen cube per day (1-sided screen), or
10 pinches of flake food per day (2-sided screen), or
5 pinches of flake food per day (1-sided screen), or
10 square inches (60 sq cm) of nori per day (2-sided screen), or
5 square inches (30 sq cm) of nori per day (1-sided screen), or
0.1 dry ounce (2.8 grams) of pellet food per day (2-sided screen), or
0.05 dry ounce (1.4 grams) of pellet food per day (1-sided screen)

[Floyd R Turbo]

You just confirmed my point. In that feeding equivalents list, it says a single sided screen has half the capacity of a double sided screen. It is just another way of staying that a single sided screen needs to be twice as large as a double sided screen in order to equal the filtering capacity.

Putting all 12w on one side would just increase the intensity to the "high light" level, meaning you could (potentially) only run them 1/2 the time per day. It does not increase the screen filtration capacity.

[acorral]

So you agree that you need twice the watts for the same cube capacity if you do it single sided? That was my initial statement

As you said you need ti double the size and if you double the size you need to double the light

[Floyd R Turbo]

No, wattage is directly related to capacity, as is screen size (physical area).

Going by the "standard guidelines" for a 1 cube/day screen, a double sided screen is 12 sq in with a total of 12W of light on it, split between both sides. A single sided screen would be 24 sq in, with 12W of light on it, all on one side.

The true method of screen sizing is actually based on the surface area, not the dimensional area. A 1 cube/day double sided screen, 3" x 4", actually has 24 sq in of growth surface - 12 sq in on each side. The watts/sq in is actually 0.5 (6 W on each side, each illuminating 12 sq in). So in order to get the same light coverage on a one-sided, 1 cube/day screen, you need to illuminate a total of 24 sq in of surface growth area with 0.5 w/sq in, which is 12W total. This is all for the "normal" light level per the "standard guideline".

The reason we don't talk about growth surface area, but instead talk about dimensional area, is because it is much less confusing.

[acorral]

Sm's original post talks about half capacity for a single sided screen with constant wattage and same size, not what you are saying...

Based on what you are saying how many total watts would a 3x4 screen requires?

[Floyd R Turbo]

The original guidelines:

http://algaescrubber.net/forums/show...E-SCRUBBER-FAQ

Scrubber Quick Guideline:

0.5 actual (not equivalent) fluorescent watts per gallon MINIMUM [0.13 watts per liter].
1.0 actual (not equivalent) fluorescent watts per gallon for HIGH filtering [0.26 watts per liter].
1.0 square inches of screen per gallon, with bulbs on BOTH sides (10 x 10 = 100 square inches = 100 gal)
[1.64 square cm per liter]
2.0 square inches of screen per gallon, if vertical but lit on just ONE side. [3.28 square cm per liter]
4.0 square inches of screen per gallon, if HORIZONTAL [6.56 square cm per liter].
1.5 actual (not equivalent) fluorescent watts per gallon if HORIZONTAL [0.4 watts per liter].
18 hours of lights ON, and 6 hours of lights OFF, each day.
Flow is 24 hours, and is at least 35 gph per inch of width of screen, EVEN IF one sided [60 lph per cm].
Very rough screen made of roughed-up-like-a-cactus plastic canvas.
Clean algae off of screen every SEVEN (7) days NO MATTER WHAT YOU THINK.

The more recent guideline is what you posted. I believe there is an error in this statement...

An example VERTICAL waterfall screen size is 3 X 4 inches = 12 square inches of screen (7.5 X 10 cm = 75 sq cm) with a total of 12 real watts (not equivalent) of fluorescent light for 18 hours a day. If all 12 watts are on one side, it is a 1-sided screen. If 6 watts are on each side, it is a 2-sided screen, but the total is still 12 watts for 18 hours a day. This screen size and wattage should be able to handle the following amounts of daily feeding:

...because it does not make sense that a single sided screen would need to have 2x the light on it and be the same (dimensional) size, yet still only have 1/2 the filtering power. Nowhere in that above statement does he say that a one sided screen with all of the light on that one side makes the capacity double so that it equals a double-sided screen of the same size.

This has always been the rule. I think he just mixed up 2 methodologies here - the single sided screen, and the high wattage technique. The high wattage technique allows you to run the lights less hours (provided that all the light is captured by the screen) but does not increase capacity.

[acorral]

Less capacity on a same size screen with same wattage on just one side is because roots die faster

http://algaescrubber.net/forums/show...ll=1#post13609

If all the watts are on one side, you can feed half as much, because the roots die faster.

As far as I understand and makes sense to me is that light is related to size no matter if one sided or double sided, the algae on that amount of space requires that light, but uf you only light one side roots die faster...

SM... Any word on this?

[SantaMonica]

If 1-sided, it needs twice the light for the same X by Y screen.

[Floyd R Turbo]

That's news to me. When did you decide to change that recommendation?

This still doesn't change the filtration capacity too, does it? I'm assuming not.