Essentially, I bought a small plastic trash can from WalMart flipped it upside down and run a 2" PVC pipe through it. The pipe has about a 1/4" slot on the bottom that the screen slides into. The screen has zip ties which block the screen from slipping all the way through which allows me to slide the screen in and out from the top. The top of the pipe has a 1" slot cut out. The 1" slot is where I can pull the screen out for cleaning and since this is directly fed by my overflow box the 1" slot on top also serves as clogged overflow protection. I then bought a 8" cement mold from Hobby Lobby. It's essentially a 8" plastic square shaped pan that is 2" deep. I cut out a 6" square from the middle and put in a heat sink with five 1 watt LEDS wired on. The low wattage on such a large heat sink guarantees that I won't start a fire. I then cut out a 6" square from the side of the trash can directly in front of where the screen hangs. I glued in an acrylic window and I place the lighting box over that. This garuntees that my LED's are 100% separated from splash. On top of that, I have a nice little window I can peek in. Finally, I made a little 6" tall shelf in the sump to hold the trash can high enough. Since the open side of the trashcan is submerged, I have 100% containment of all the splash and on top of that is is very quiet. Much more quiet than the air pump running my old up flow algae scrubber. Attached are pics of the apparatus. The last picture is the screen 5 days after start up. I'll give you all another update on this Friday which will be 12 days after start up. Also note in the side picture you can see where my overflow box ties into the scrubber.
Slightly late update. I took the photos yesterday I just didn't have the time to post them. The screen is growing in very nicely and based on the rate at which it is growing I think I can expect to be cleaning this screen next Friday! I am extremely happy with the waterfall scrubber thus far!
Nice build! Looks like you are getting fast growth too. What is your LED array configuration? # of LEDs, brand, drive current, etc
It's 5 of the Philips LED's (the ones you recommend) running on a 350 mA dimmable driver. I'll probably upgrate to 700 mA dimmable so I can output more light in the future. Right now the whole thing heats up to a whopping 80 degrees Fahrenheit Driver is a 350 mA flexblock A011 ($20) Heat sink is a 6.080" low profile from www.heatsinkusa.com (~$10) The enclosure is a 8" square cement mold from Hobby Lobby (~$10) Power supply is just your standard switch mode power supply. I got mine from digikey.com but you can get them anywhere...mines a 24v but with the flex block you can use whatever you want as long as it has sufficient wattage.
Herewith an update (it's been a really long time). I've been getting consistent growth but in my opinion not enough. I've scrubbed the thing maybe 4 or 5 times and I kept forgetting to update you all on the status. I get rather dark growth so I've decided to bump my light system from 350mA to 700mA to see if more light does the trick. Here are some picks of my latest scrub. Any tips or advice is always helpful
A few questions: how big is the tank? how much are you feeding? what is your photoperiod? what is your flow rate across the screen? On your LED array, is that 4 660s on the corners and ?? in the middle?
I think I'm running the lights for 14 hours a day (opposite to the main lights). The tank is 40 gallons. I feed about 4-5 cubes a week (I should probably feed my fish more often). I would estimate the flow across my screen to be maybe 250-300 gph. All of my overflow is going through the scrubber before it reaches the sump. I could do a flow test but I would need to get pretty creative on how to test the flow rate properly without leaking water everywhere.
Is the scrubber doing it's intended job? i.e. nutrient in check, no DT algae? I've had this type of growth before. Tell me if I'm right, but you have a base of GHA that is covered with a slime coating of dark brown/black slime. This stuff smells horrible (putrid is the word I use), very similar to the smell of Anthelia when it is exposed to air. You can swipe it off with your hand and rinse it off the screen, and the smell almost instantly goes away - the leftover growth on the screen is nearly scent-free. If the answers to this is yes, then you are over-lighting the screen. Strange as it sounds. I saw this first on my first UAS test unit. When I blasted the new screen with light, this is almost all that would grow, it looked like dinos in that unit. When I backed off the light, I got less of it. When I split up the photoperiod, even less. I then noticed it again on the same tank when running a waterfall unit (same LED array) when I was running the LEDs too long. I backed the light off and split up the photoperiod and got less of it, and eventually it went away completely as the GHA on the screen really took off. My theory on this is that the algae can only adsorb so much incident light energy, and anything that is in excess of this over a prolonged period promotes this dino or diatom type of growth. Since you probably can't easily increase your flow, I would split up the photoperiod into 3 hour chunks with 30-60 minutes in between, total of 9 hours on time. This also assumes that your DT nutrients and algae are under control. The idea here is to give the algae enough light to grow, but to cut that light off before the dinos start to take over and let the GHA "get ready" for the next cycle of light. You can try to run the lights at higher current during these shorter cycles, but then that's changing 2 things and you won't know which one did the trick. Theoretically running a shorter cycle with higher intensity light should give you good growth, but then it comes down to the same issue, too much light in that period of time would tend to promote the slime growth. Also if your DT nutrients are under control, then increasing the flow is not likely to do a whole lot, because while you may be delivering more nutrients per unit of time, it's not a whole lot more. If you had elevated nutrients, then increasing the flow would probably offset the over-lighting a bit. I do have an L4 running on a 220, alongside a skimmer, sock, and carbon (which is only changed every 2 months - not my tank, but one I clean the scrubber on) and that one which runs 12 hrs/day and no DT algae, N=0 and P=0.05 gets a lot of the gooey yellow growth, but ti does not smell that bad. It's been pretty consistent that way for a while also, so my thought on that tank is that it is on the edge of over-lighting, or there are enough nutrients to support the yellow growth but it's not overlit enough to promote the dino/diatom growth. The screen is also somewhat bare in the middle so I know that it's overlit, but the tank has a piggie 10" Vlamingi, 8" Hippo, 8" Blonde Naso, 5" Yellow, a few clowns, and a handful of damsels. So it has a good bioload, which might make the difference.
Also with this type of growth, don't vigorously clean the screen. Swipe the goo off, and give it a light scraping, but leave most of the GHA on the screen. The LEDs penetrate deep so you don't have as much to worry about with the screen dying off at the lower layers. The more GHA you leave on the screen, the more incident light it can adsorb. If you scrape it all clean, then the dinos/diatoms get started more easily.
Well luckily I do have a way to increase my flow if necessary. When I first installed this pump I knew it pumped much more than the tank could handle so I put in a bypass valve which is partially open at the moment. The bypass just dumps water back into the area where the pump is pumping out....so I could just tie that into the inlet of my scrubber to get more flow (and get sort of a re-scrub effect). I'll leave the light as it is for now. I know you know what you're talking about but I soldered that sucker in. Plus, like you said change one thing at a time. If over the next few weeks I get a spot in the middle or it slimes over then I'll pull out the soldering iron again. The algae didn't smell bad. Just smelled like the ocean. And I also need to start manually removing the algae in my main and change out the bulbs in my tank because I think there is enough red light and algae in my main to compete with the scrubber. In the mean time I may or may not tie the bypass into the scrubber.
I took a look at the screen today. It's not too bad but I didn't wipe it off completely. I just barely scrapped off the very top thin layer. All that came off in my light scrubbing was green algae...nothing slimy so that is good news. So maybe I just don't clean my screen as often? I decided to bump my photo period to 13 hours instead of 14. If you still think it would be better to do blocks of 3 hours on then I will give that a shot. I also did slightly up the flow rate across the screen (more flow into my display which in turn increases flow to my scrubber. Didn't seem to increase my growth but everything in my display looks better.
I have to d/l the pics off my phone but I went in to service a tank today and realized that I had gone 19 days between cleanings. the growth was enormous but the lower layers were still solidly attached and no dead growth down deep. It was pretty insane growth, I'll try to get it uploaded but I'm working today (real job stuff) so I'm trying to avoid distractions. As long as you are using DIY LEDs like you are, I would not worry about lower layer death and just let it grow out longer and longer each time
It's been 20 days since I cleaned off my scrubber so I figured it's a good time to do it. I got a little bit more growth than last time I think but not enough to impress. I think my next step will be to increase the flow a lot more. Anyways attached are some pictures. You can see it's definitely not slimy stuff. But it's just not ginormous like the screens I see on this forum sometimes. I took pictures of the front and back of the screen before and after I scrubbed it. I didn't scrub the back in hope that it will help start the next harvest. P.S. - My nuisance algae is definitely going away. It does not grow back nearly at all and the parts that do grow back are slow enough to manage. The main used to grow algae like crazy and extremely fast.
Looking better, a little at a time. Thanks for keeping the thread updated, I'm interested to see the progression.
Update: I went on a nice vacation to Florida over Christmas break and when I got back on New Years Eve I took a look under the hood. The growth looked more hairy and green than last time! So this growth is over 4 weeks time. I've been keeping any eye on the screen over the past couple of days and it does seem to be growing back faster. I will start scrubbing less often to try to get the good stuff to grow in. I also think the screen does not fill in as fast due to how much (or little) I feed. I feed my system maybe 1 cube every other day. And over the break I did not have anyone at the house to feed them so they were on their own for a week.
I guess it didn't dawn on me until just now but this is a single-sided scrubber, correct? The growth doesn't really look that well attached, maybe that's from the length between cleanings. The brownish stuff in the holes kinda looks like detritus, I wonder if there is some decayed growth on the back side of the screen. I wonder what would happen if you put a single LED on the back side? The idea is to give just enough light to the other side to boost the attachment of the growth on the other side. Even a really small CFL maybe. Just a thought.
Yes it is a single sided and you do have a point, the backside is always this ugly bownish color. Getting an LED or two on the backside could prove to be tricky but if I get some time perhaps I will give that a shot. I have another "single sided" concept that I am working on at the moment. It is basicaly just a sump with a really high wall that the screen goes against. Maybe it will help prevent the backside from grabbing detritus. I will post the current construction of it in another thread. I may or may not scrap the whole idea because I think the classic double sided waterfall style is pretty robust.
Also, the growth isn't falling off but it is getting scrapped off when I remove the screen for cleaning. The screen just slides into the slot which I think is the biggest pitfall of the design. This last cleaning I had trouble pulling the algae through the slot and some peices did get scrapped off in the sump. This is what sparked the concept that I will post in another forum later tonight.
Another update, Cleaned yesterday the 22nd which means 17 days of growth. I have started weighing the growth. This time it weighed 12 grams after a good squeeze. I cleaned a little less liberally and I left the backside alone in hopes that the next grow period will be faster. The back size looked a lot more green. I think the biggest improvement this round was the increased flow rate.
