Hello all first post be gentle. I was thinking of hanging an acrylic sheet from my first sections overflow baffle running it down 45 degrees into my second section. I was hoping the flow through the first section would be enough to prevent the need of an additional pump in a vertical type scrubber. Are there any problems with this ie more light required etc? Thanks for any help.
You mean solid acrylic? It's best to add a standard plastic mesh screen to it (roughed up) to provide settlement (growth) areas. If you can somehow "pulse" the flow from the first chamber over the screen, to the second, it will help.
Hi Garf, Yes was going to run a solid acrylic sheet down at at 45degrees from the baffle like a slide then attach some mesh to it with cable ties so they could be released easily for cleaning. Water will hopefully flow quite evenly over the width if level, return pump is an eheim 3000. Not sure if I can post links but like this (please delete if not), a picture is better: http://www.ultimatereef.net/forums/showthread.php?t=690351 I just see a lot of vertical type designs but this seems quite simple and uses the flow through the sump. Thanks
Stay away from bubbles in my view. It creates excessive shear flow which may inhibit growth. Edit - you could perhaps use bubbles to create glimmer lines on the screen (off to the side of the scrubber, perhaps even like an airlift tube which would break up the laminar flow a bit)
Welcome to the site @Anton and yes, links are permitted for sure! I'd say that your plan sounds good, the biggest factors for any scrubber are the screen material and roughness, flow, and proper lighting. As you can see in that UR build, the lighting doesn't have to be perfect to work well enough to outcompete the algae, but if you're going for maximum efficiency, then you want to try to get the right light spectrum and coverage on the screen. I used to say that anything that was 'slanted' was considered 'non-vertical' for sizing calculation purposes, but I have since reversed that thought. They are still one-sided, but the more slant you have, the thinner the water profile is over the screen. This is important because a flatter screen will have slower moving water and the screen will be 'deeper' below the surface when compared to a slanted scrubber, for the same flow rate. For a slanted scrubber, I would still err on the side of larger, meaning, make it as large as you can for the space you have. You can always reduce the size later.
Thanks Floyd, I have read a lot of posts on your site and like your open minded and reasoned attitude. Will give it ago and post pics and progress as we go. I think I will try 2 of the 10W floodlight lights that are used in that post and vary the angle of flow to see what suits. Just need to paint the stairs and hallway first to accrue my tank build points now.
I'm also looking at making a horizontal algae scrubber. In the past the consensus has been that you need to have 4x the size screen for horizontal as opposed to vertical. Is this still the case? Surely as long as your lighting and flow is good they will be quite close to the performance of vertical scrubbers? Surely they are significantly better than UAS scrubbers.
A flat/level scrubber will lose a lot of efficiency because the rate of flow is largely dependent on the input (pump, etc). As you apply a slant angle, efficiency does go up, but there is likely an upper limit. The other factor is that any non-vertical screen will be one-sided by definition, meaning it will have to be 2x the LxW no matter what. Then, since you can't light the other side, you will have a higher probability that the lower layers will not get enough light/nutrients so you lose some more efficiency there. So there are a few things to consider. Another thing worth noting is that the more efficient horizontal type of units are of the dump bucket or surging style. So a static horizontal would be the least efficient overall of any scrubber type. After that, if I had to take my best logical guess, that would be followed by a low-angle slant (say, 5-15 degrees), but then after that I'm not sure which would be more efficient, a steeper slant or a horizontal with a high frequency of dumping or surging. When comparing a horizontal dump/surge to a double-sided vertical waterfall, I would be very interested to see exactly how these match up. I know that the "horizontal must be 4x the size of a double-sided vertical" was really just a stab in the dark, and on top of that, it was made back when scrubbers were sized according to tank volume. So really, even 6 years after the vertical was introduced, it's still a rather unfounded comparison...but it's probably relatively close. Dump bucket scrubbers were never sized by feeding. I have Dynamic Aquaria, but that book is more complicated than most of my Electrical Engineering textbooks from college. Comparing the complexity of electromagnetic field theory (the class I still have nightmares about) and Dynamic Aquaria...I would probably find DA more interesting but talk about bedtime reading zzzzzzzzzzzzzzz
Sorry, when I referred to horizontal algae scrubbers I meant slanted horizontal scrubbers, 20 degrees slant approx. I don't think the issue of having to be twice the size is a problem, I think even at twice the size they still take up less important space than vertical ones. There's often lots of spare horizontal space inside a tank that can be used for a horizontal slanted scrubber, whereas vertical ones (while they are great performers) just don't suit a fair few people due to the lack of space required above the tank or sump. I reckon that's pretty much the only reason why the SM scrubbers upflow scrubbers got quite popular, due to the lack of space required in/around your tank, that and maybe price. I'm building one currently and I'm going to have it all encased in a rectangle enclosure made of white acrylic, the algae screen will be mounted on clear acrylic and will be lit by LED's from above. So some of the light will (in theory) bounce of the bottom and side of the white enclosure and reflect back up through the transparent acrylic into the bottom of the algae keep it alive. In theory anyway. But I think it will work. I'm also very interested in the copepod production of horizontal scrubbers purely because of whether or not a scrubber can completely sustain a mandarin dragonet. They are never recommended in anything close to a small reef tank, so I think it'll be a bit of a breakthrough if it's determined an algae scrubber is all you need to produce enough copepods.
I wonder what would happen if you rotated your screen through 90 degrees regularly. If it was easy access and the screen just hooked on you could easily turn it round to alternate flow. Like browning a piece a toast under a grill.
Yeah, I've thought about having a piece of screen wrapped around a small cylinder that slowly rotates, half of it is in the water at any one time, it's lit at the top (so while it's not in water but is still wet). That way you'll have quite a lot of screen in a relatively small space and lighting would be a breeze. Downside is probably the difficulty to harvest the algae, but i'm sure there are smart ways around that to make it easier.
