My current design

[MorganAtlanta]

I've had several different scrubbers over the last several years. I never seem to be able to stop tinkering with them. Here's my current design.

It's a single sided waterfall made out of a black acrylic magazine holder from Target. I glued some scrap acrylic for legs and put a 3/4" bulkhead in. I put a pipe in the bulkhead with a number of holes in it to spread the flow out, and put a piece of egg crate on top of that, which makes a nice media tray. I've got about a gallon of Seachem Pond Matrix in the tray. The water comes from the drain flex pipe into the box, flows up through the media, then overflows the side of the box I cut down about 1/2 inch and calmly and evenly waterfalls over the screens. The screens are held on by spines from plastic report covers. The screen area is about 12" x 10", in two pieces. In the pictures, I'm starting a new screen on the right with a piece from an old screen.

The lights are LEDs on two 6" x 10" heatsinks. 16 3W reds (run at 600mA) and 9 1w blues (run at 175mA). Current cycle is 7 on and 9 off. I'm experimenting with different cycles. The lights sit outside the sump (a standard 29 gallon). The normal water level is right at the base of the box. With the pumps off, the water rises up, but there's no danger of overflowing, and I don't get any build up on the glass in front of the lights at all.

The setup is super simple with no spray/creep problems, and I can take the screens off for cleaning without even turning off the main pump.

I know double sided scrubbers are supposed to be "more efficient", but this set up seems to be working as well or better than my previous double sided waterfall for my needs, and it takes up less space in the cabinet, and is much easier to clean.

I'm feeding 2-3 cubes of mixed frozen a day, but I'm also running a skimmer, so I don't know which proportion of the nutrients are making it through to feed the scrubber. Nitrates are at 2 ppm, and phosphates were 0.1 ppm and trending down at last measure a few weeks ago. Last big water change was a year or more ago, but I have done a couple 10-15% changes.

I tried scrubber only for about two years, but always battled algae, no matter what I did in terms of size/light/flow on the scrubber. The current combo to ASM G3 skimmer and the scrubber has pretty much cleared up algea and cyano from the 125 gallon display.

If you are considering a UAS, you might want to try this waterfall design instead.

[Garf]

Nice write up. Good to see different approaches.

[Ace25]

That took me waaaay to long to figure out what the heck I was looking at. LOL. Really hard to figure out even with the pictures, but after 5 minutes of studying it I think I figured it out.

It seems like that design requires a pump to feed it but yours is fed by the overflow. Are you are only using holes at the bottom for the flow, what happens when the pipe/holes get clogged? Wouldn't the tank overflow? Thinking about it a little more, it seems like using an over sized return pump (but still under rated compared to your overflow capacity) and Ting off to feed the scrubber would be pretty ideal because even if the scrubber box clogs the worst that would happen is you would get more flow into the tank.

Man.. this thing has got my brain working in overdrive now.. good job on that. LOL. So thinking about it even more, it actually seems similar to my HOB concept, only in reverse. On my HOB concept I used the UAS method, then had the water overflow into media chambers, where as yours feeds up through the media chambers (making more like a reactor) and then overflowing onto the screen. Honestly, I like your idea better than mine even though mine is double sided.

[MorganAtlanta]

The holes you see in the box aren't really holes anymore. I covered them with clear acrylic. I can see where that would be confusing. It's pretty much a just box that stands on legs, with a bulkhead on one side near the bottom. The holes in the pipe won't clog because they are big, and they are in the dark, since the box is black acrylic. The pipe just helps spread out the flow so the waterfall is smooth. Actually, with the media in the box, it is really unnecessary to have the pipe at all.

Before I had the media in there, I had a problem with too much turbulence in the box and the flow over the waterfall being "bunched up" at the opposite end from the bulkhead. The pipe with holes (a dozen or so 5/16" holes) served to even out the flow. The media does the same job.

Also, since the outlet to the drain is under water, it would be working at full siphon. It's on a Herbie style drain.

[Ace25]

I was thinking more along the line of algae/debris/snails from the display tank clogging the holes in the pipe, not algae growing on it from the light. I just pulled out a couple pounds of algae out of my display last night and it partially clogged my slot. I have that happen all the time on mine, algae from the display clogs parts of my slot which in turn makes it 'pee' streams out of spots. Easy for me to hear when that happens though and a quick swipe of a credit card between the screen and slot clears up that issue quickly on mine. Plus I have an emergency overflow at the end so my tank never overflows, and it has come in use quite a few times successfully. If you take off the pipe, then ya, no issue anymore with your design.

[MorganAtlanta]

I've got a screen with 1/8" slots at the top of the drain, so that's not likely to be an issue. Also, 5/16" holes are relatively big, and there are more than are necessary for flow, they really serve just to spread the flow so it isn't a jet coming out of the bulkhead.

[Floyd R Turbo]

Nice!