Originally Posted by
Floyd R Turbo
Ok, the rule is that you start with the size of your tank (display only, and don't subtract rockwork, etc), in gallons. Then, you measure your flow rate either into your sump or out your jets (this means actually taking a container and timing how long it takes to fill it up, repeating several times, then extrapolating this out to GPH). Take your actual flow measurement result and divide by 35. This will give you screen with in inches. Take that number and divide into your tank size, and this will give you your screen height.
For example, let's say you had a 90 gallon tank, and your pump push 300 GPH (measured). 300/35 = 8.5 inches. 90 / 8.5 = 10.5 inches. Thus the optimal screen size would be 8.5 inches wide by 10.5 inches tall.
As far as the conversions go, because the screen size has a nice easy correlation between gallons of tank size and square inch dimensional area (L x W = tank) it is easiest to work in those units. That is probably your issue. I would convert your tank size from L to G and flow rate from LPH to GPH and work the calculations, then convert back to metric once you have figured out your necessary total square inches (L x W)
Also note that this works for a screen lit from both sides. If you only light from one side, the L x W dimension must double.