Algae Scrubber Basics
Start on post #33 that is the latest update. Screen size is no longer based on tank volume, but rather on feeding.
My current recommendations is a hybrid of both, in a manner. #1 size based on feeding, but #2 also account for tank turnover rate across screen.
Not sure what the "rule of thumb" really is here, but I think at least 1 turn/hour over the screen is a bare minimum, and probably along the lines of 4/hour is good to shoot for. So for an 80 gallon tank you want 4x80 = 320 GPH
over the screen, but that means a 9" wide screen (35 GPH
/in of width) and unless you're feeding a lot, like 4 cubes/day which would be 4x 12 = 48 sq in, 9" wide means 5" tall, that's an odd size.
So instead maybe shoot for 2-3x turnover rate, which would be a 6" screen (210 GPH
) and then the height per feeding, so 6x4 - 2 cubes, 6x6 = 3 cubes.
The 'turnover rate' is really something that I extrapolated from the extreme cases. Say you're feeding a 400g tank 2 cubes/day. Well a 6" wide x 4" tall screen would cover that based on the feeding guideline only, but it takes 2 hours to turn over the tank water. Over the long run, you're giving the algae in the tank more time to absorb nutrients instead of the scrubber being able to take care of it. In such a case you would likely want to opt for a wider scrubber, even though it throws off the cube/day rating a bit.
I don't know if I have now thoroughly confused you or not.
BTW terrance thanks for the plug