DIY Algae Scrubber

Looks like good flow rate. Did you rough up the screen? Can't tell from the pic. It needs to be really rough

As for the lamps, are you using 60W CFL? Is that the "incandescent equivalent" rating, or the actual wattage? I'm guessing it's the former - I don't think they make a 60W CFL (and if that's what you're using, it'll burn the algae)

I'll have to check again, but I think you really want the 2700-3000K lamp temp for the scrubber. You'll get algae with just about anything, but this light temp works best. I'll let you know. I've never actually built one using CFLs.

 

For roughing up the screen, use a core drill (like for cutting a doorknob lockset hole) take the drill out and use that to rough it up. Press moderately and randomize the motion, back and forth, circular, etc. Go for about 20 minutes on each side. Screen should be almost to the point of falling apart at the edges. The stuff is tough, it takes a lot to rip it apart. Mine started to rip at the edges, that's when I knew I was getting close. For a 10x10 screen it should take about 30-40 minutes. Seriously. Rough it up big time.

 

Once the tube and screen build up a little slime, the flow should even out a little more.

However, if the slot is not the same width all along, there might be variations in flow over the long term. Cutting the slot is the most difficult part of the scrubber build. I still have to fix mine and you've seen how well it grows even improperly cut.

The trick is to make the slot 1/8" thick and as perfectly straight as possible. The screen is 1/16" thick so that give you 1/32" on each side. Any wider of a slot and the water will exit more at that point, giving you uneven growth. This should settle out a bit over time.

Bottom line is that you can fix that later. Getting the screen rough and the light right gets you quite a ways and that has to be done correct from the start.