So I was playing around with screen and slot pipe size and ended up throwing away my mature screen only to decide that my original screen and slot pipe size was the best. I replace the 5"x9" screen with a brand new roughed up screen 3 or 4 weeks ago. But now the growth I'm getting is really strange,I am getting nice thick green growth on the bottom left hand corner of the screen but nowhere else. The rest of the screen keeps growing this chocolate brown algae like stuff? The brown growth does not wipe right off like jelly but it does scrape off much more easily than let's say turf or hair algae. When I clean the screen it is left bare white with the exception of the green corner . I have noticed that when my pump has been freshly cleaned it has more than enough GPH for the 5" screen,,but after a month I lose almost half of that flow. ( monitoring flow with stopwatch and gallon jug) . Is the low flow causing my strange growth?
Ok here are some pics. Strange I just went down to clean the screen and take some pics and the growth looks a lot better today! But you can still see where that brown growth was,the holes just don't like to fill in where that stuff grows.
Here are some shots of the tank just for fun! it was skimmerless ATS only for about four years but I threw a skimmer on it six months ago
The light may have been a bit too much for the bare screen, but it was perfect for your mature screen. What you are describing seems to fit that scenario - you get green growth around the edges (where the light is weaker) but near the middle, where the light is very intense, you don't get much. This will get better as the screen matures and fills in, and is able to "use" the intense light in the middle. As for the flow issue, what pump are you using? It may be one that does not have good head loss characteristics, and as the growth cycle progresses, more algae grows toward the slot/screen junction and this causes backpressure. That's why I designed the light/spray blockers and you can buy those individually, they are only good for use on 3/4" pipe though, not sure what you are using.
Thanks for the reply. My scrubber is fed directly from the overflow via gravity,my return pump is a 700gph sun sun brand,(China). I know,I know lol. But the pumps have plenty of power,are quiet,and last for about two years,all for $35. I will take some pics of the pump and plumbing soon. As a side note,the screen was almost all green hair today! I did a partial cleaning the HA was coming off in sheet form though,maybe it needs more time?
Your screen looks like it is 4.5" wide, so 4.5 x 35 ~= 160 GPH, you should be fine there with a 700 GPH pump minus head loss. Sometimes it's hard to say if there is anything wrong with a scrubber setup until you've given it a chance to mature. I can predict and troubleshoot my units with pretty good confidence on my suggestions, but a DIY build is dependent on many factors like screen roughness, slot width, flow rate, LEDs (brand and quantity), photoperiod, distance to screen, drive current, flow rate, etc. Also things like flow rate and photoperiod can be somewhat dependent on one another. The other factor is the initial tank condition. This is highly variable and can be the source of a myriad of issues. For a long time, my scrubber grew thin and dark green and I only needed to clean every other week. Then about 3 months ago, my growth just exploded and I changed nothing, now I have to clean every 7-9 days and I have not explanation for that.
God eye! The screen is 4-7/8" wide and about 10" long,but about an inch and a half is under water. My slot is a little extra wide,I made the slot by using two de-Walt multiple purpose 10" table saw blades sandwiched together. It's a hair wider than 1/8". The LEDs are Phillips from rapidled.com. I have 4 660 deep reds and two royal blues on each side. They are all run full power on the (non dimming)mean well driver sold on rapid.
Standard table saw blades are 1/10" wide so your slot is probably bigger than 1/8" if you offset the teeth when sandwiching the blades together - maybe 1/6". That should be fine as I'm guessing you are well over the 160GPH. If you have very high flow initially, it might take longer for growth to get a foothold. But once it does, you should get good results. What I usually recommend is the standard flow rate and conservative lighting initially, so that you don't wash growth away or photosaturate whatever growth is there. Then once you have a base of growth, you can increase the flow and lighting (photoperiod or intensity, or both). Your LEDs are probably OK, 40 sq in lit by 4 reds is one per 10 sq in which is on the low end of the intensity range but the blues make up for a bit of that. I noticed that you have an acrylic splashguard over the LED array, is this clear or is there a diffuser in place, frosted acrylic, etc? Salt creep on the splashguard might cause a bit of diffusion, I would keep this clean or get a can of LED Seal and spray the array (this waterproof the array to the point where you can actually submerge it)
Yeah that splashguard is pretty gunked up!! You're losing a lot of intensity because of that I think. Your growth is filling in but still pretty dark, it might do OK for you though. If you replaced the splashguard with a new one and kept it clean it might help. You could probably add a few more deep reds also and up the overall intensity. Nice emergency bypass setup. I see you read about that! Edit: I fixed your post. It's a good idea to hit Enter before attaching pics or they end up inline with the text. Then hit enter again after the last pic before adding more text. This puts the photos/thumbnails on their own line
Thanks for the tips,I will try to keep it clean. Not to toot my own horn but I made that bypass WAY before reading about one! One day when the kids are older and I have more time I would like to re-do the whole set up to make it more professional looking,maybe even purchase a pre made scrubber! I cleaned the scrubber today and all tho the growth was all green hair when scraped off it left more than 50 percent of the holes empty.
