Need help with overflow box

[SuperFudge]

Average fingers on the overflows are 1" long.

If you have a laminate trimmer(small router)you can purchase a 1/4" flush trim bit to cut slots if you want them nice looking.
You will also have to make a small template...this you can do with a small piece of hardwood(the bearing on the bit will ride on this template) and cut it out just as you would the overflow,then you can do as many overflows as you like.

Or,if you dont really care about aesthetics you can just set up a small stop block on the table saw and just rip a bunch of slots...but its easy to break the fingers off this way.

FWIW,i probably have 15-1600 gph going over two 6x6 overflows...fingers are 1" long and water builds about half way up them before spilling over,if i had to make them again i probably would have made them about 1-1/8th"
long...

HTH,Marc.