Scrubber problems (light)

[PeterFranc]

I built a scrubber and have had little luck with growth, I keep getting brown algae which eventually leads to dark purple (cyano) algae. I checked out the FAQ on here and saw the landscape light Santa recommended but I don't want to spend 70 dollars. I also found in the FAQ 3,000k is the best spectrum. I've tried CPL's but still am having little luck. I used sandpaper on my screen, I will use a hole saw and get it even more scuffed up. I noticed some people use flood light bulbs on their scrubbers instead of the coil styled? Are these better? At the home depot I found a Bright White r40 flood light that was 23 watt-120 watt equivalent, 3,500k.

Currently I have 2 cpl's on each side of the screen, they are either 100 or 120 watt equivalent I can't remember. Also worth noteing the nitrates are around 180ppm so I'm not sure if that has anything to do with the dark growth.

Here are a few pictures of screen growth.

Thanks, I can't wait to get my scrubber working so I can see my fish happy.

[sklywag]

I'm using the same style of bulbs but with reflectors. Those spot lights work nice due to no reflector needed. Screen is nowhere near the amount of roughness needed. It needs to be dang near shreaded. Not quite but it needs to be really rough.
You can see some nice green color there. So clean it, rough it up and put it back to work. Looks like good coverage with lights. Just need to give algae something to hold on to.

[SantaMonica]

Put a timer on the light, 18 hours.

Put a reflector on the bulbs.

Use the hole saw.

Put two more bulbs if you want to power yourself out of the high-nutrient situation faster.

Cut feeding in half for 8 weeks.