For bigger pods, use rock rubble. Chaeto will die.

Use this to figure flow:

Screen Width-----Gallons Per Hour (GPH)

1" 35
2" 70
3" 105
4" 140
5" 175
6" 210
7" 245
8" 280
9" 315
10" 350
11" 385
12" 420
13" 455
14" 490
15" 525
16" 560
17" 595
18" 630
19" 665
20" 700
21" 735
22" 770 -- SM 100 size

If you are doing an overflow feed, the overflow will determine how much flow you have to work with. You have to start from there, and size your screen accordingly. The maximum flow you'll get to the screen will be what's going through your overflow now. This is easy to figure out by counting how many seconds it takes your overflow to fill a one-gallon jug:

60 seconds = 60 gph
30 seconds = 120 gph
15 seconds = 240 gph
10 seconds = 360 gph
8 seconds = 450 gph
5 seconds = 720 gph


Take this gph number that you end up with, and divide by 35, to get the number of inches wide the screen should be. For example, if your overflow was 240 gph, then divide this by 35 to get 6.8 (or just say 7) inches. So your screen should be 7 inches wide.

How tall should the screen it be? That is determined by how much screen area you need, which is determined by how many gallons you have. Try to get one square inch of screen (lit both sides) for every gallon. If lit on only one side, double the screen area.

When finished, this is how you want your flow to look: