Algae Scrubber Basics

[srusso]

There are over 7,000 different species of green algae, mostly aquatic, if someone else has a nice species of green hair algae inoculating your tank with some might not be so bad, once you properly design your algae scrubber, having good green hair algae is a good thing. You can't expect all the different species to be in a single reef tank, so if someone else has some good species growing in their tank, why not grab some? The whole point is that you want the good green hair algae in your system, just not in your display. srusso I'm merely saying it doesn't hurt anything.

I guess that's possible but to have NO green growth of any kind? Impossible... Something isn't right

 

[Floyd R Turbo]

I tend to agree which is why I need to see pics.

 

[aquaenthusiast]

I guess that's possible but to have NO green growth of any kind? Impossible... Something isn't right

Maybe it's possible that starting out with dry rock limits how many green algae species you have in your tank making it much harder to start initially. It could also be the water flow, the lighting, the nutrients, they are a lot of factors that could contribute to little growth...

 

[Anycall2]

Led design question - ats

Led design question - ats

So, I've modified my ats a few times... Moving t5s to cfl and going to LEDs. I want to make a 3x4 ats, but using your stated specifications... I would get 1 3-watt red led in each side... My question is do you get a driver just to power two LEDs?

 

[der_wille_zur_macht]

As a recap, this tank has been wet for just under 4 months. It is a 360g display, 75g sump, fairly light fish load given the size of the system. The scrubber was grossly oversized until I read the feeding guidelines which was a little more than a month ago. The aquascape was created completely out of dry, dead, man made live rock. There are a few dozen corals in the system, some of which came on very very small pieces of rock or substrate, so there has been a mechanism to introduce life into the tank, though clearly very very small compared to most systems populated with natural live rock.

Topoff via RO/DI with zero TDS, alkalinity and calcium via (separate from topoff) kalk dosing.

Food is a mixture of PE mysis, enriched frozen brine, NLS pellets, high quality flake, and recently the filter feeder formula from reefcleaners (I have a handful of gorgs in the tank).

The livestock is more or less healthy and the tank is more or less doing ok. Nutrient levels are fairly low but not as low as some ATS users report. I'm a terrible photographer but here are some recent photos:

(don't mind the closed up zoanthid frags in the one photo - was screwing with dimming the LEDs to get the photo to come out better and they weren't happy about that).

Here is the scrubber:

I took the reflectors off for the photo since they completely obscure the scrubber. They're made from an old cut up spider reflector (basically each pair of CFLs has half a spider reflector behind it.) The sump is white so there is good natural reflection, though as you can see in the photo, the entire submerged portion of the sump is covered in the same pale slime as the scrubber screen.

I was feeding roughly 2 cubes per day but upped it to a little more than 3/day around the time I re-sized. Screen is roughly 4" x 10" so I have 40 square inches, should be right on for my feeding rate (3.5 cube equivalents). The CLFs are standard-issue 2700k 23w. So I have 92w total with 46w on each side. Run 8 hours on/16 off opposite main tank lighting. So basically I'm using the "high intensity lighting" update, since it mentions being better for promoting green growth.

Flow is provided by a T off the return pump and was measured in-situ, with the whole system running and the screen in place, I'm getting ~200 gph. I measured flow by putting a container of known volume under the screen and timing how long it took to fill. So I have 50 gph per inch, which is above the suggestion of 35 gph/in, but again the guideline mentions more flow being better if you're getting spongy yellow growth instead of green growth.

I do have carbon on the tank (BRS's lignite carbon) but I'm running a little less than a third of what they suggest for my water volume. I have a skimmer - but it's insanely undersized for the system, and I only run it for a few hours a few times a week to help deal with the "slick" of organics that collect on the surface of the water in the sump, and it's plumbed "after" the scrubber anyways, so the scrubber is always getting the dirtiest water possible.

I had a very small handful of chaeto in the sump but took it out a few weeks ago (around the time the scrubber was resized). It never grew significantly other than a very short burst when the tank was initially started.

I'm fairly confident that I don't have any major "rules violations" according to the new guidelines but let me know if I've missed something.

 

[der_wille_zur_macht]

Double post!

I will take the opportunity to point out the bubbles around the scrubber in the sump are from the water coming off the bottom of the scrubber creating surface agitation.

 

[srusso]

Can you post a picture of the reflector? You seem to have the lighting wrong... Unless it was just a typo. Should be 18 hours on, 6 hours off. Also seems like an extremely low bio load for such a large tank... The live rock maybe limiting scrubber growth, due to the extremely low bio load. What fish do you have?

 

[srusso]

Maybe it's possible that starting out with dry rock limits how many green algae species you have in your tank making it much harder to start initially. It could also be the water flow, the lighting, the nutrients, they are a lot of factors that could contribute to little growth...

Your reaching... It's not the algae... please stop making things up...

 

[der_wille_zur_macht]

Can you post a picture of the reflector? You seem to have the lighting wrong... Unless it was just a typo. Should be 18 hours on, 6 hours off.

As mentioned I am following the "new high intensity" lighting guideline:

Big Basic Change #2 "“ Alternative High-Intensity Lighting

Around the same time that the screen sizing method was changed, another suggestion was made: you can use twice the wattage of lighting and cut the photoperiod in half.

Hence I have doubled the wattage per square inch and cut the photoperiod in half. The lamps were new when I resized so they're a hair over a month old. Should be barely broken in, since the new guideline predicts 6 months of life on this schedule.

Also seems like an extremely low bio load for such a large tank... The live rock maybe limiting scrubber growth, due to the extremely low bio load. What fish do you have?

Isn't the new feeding guideline supposed to account directly for bioload regardless of tank size? I thought that was the whole point. Besides, the LR isn't completely reducing/exporting nutrients as they're present in the water (and LR isn't typically attributed with the ability to process certain nutrients anyways, like P). At any rate, the tank has much less rock than a typical system of this size - probably close to 1/3 - 1/2 lb per gallon as opposed to the more typical 1 - 2 lbs per gallon.

Livestock is:
-A pair of clowns
-A pair of translucent cave gobies
-One barred shrimp goby with a pistol shrimp
-One (large) PJ cardinal
-Six blue reef chromis
-One starry blenny

Plus, a typical snail-based cleanup crew and a few dozen small corals/frags - zoanthids, LPS, SPS, softies, photosynthetic gorgs.

The fish are chubby and I don't see an obvious need for more food (especially after upping it significantly when I resized the scrubber). Some of the more delicate SPS are showing signs of being unhappy and I think I can partially attribute that to the ever-so-slightly elevated nutrient levels (in addition to the lighting being too strong for some of them).

You asked about reflector photos - sorry, I don't have any right now. It's just a typical metal halide parabolic spider reflector. It's split in half. Each pair of lamps has their own spider reflector tucked in behind it.

Your reaching... It's not the algae...

How do you know it isn't? I'm not trying to argue, I'm honestly looking for information. I really love the concept of ATS and I feel like I'm following the rules to a T, but it's not working and it's not clear (to me, anyways) why.

 

[Floyd R Turbo]

Here is the scrubber:

...I took the reflectors off for the photo since they completely obscure the scrubber. They're made from an old cut up spider reflector (basically each pair of CFLs has half a spider reflector behind it.) ...

...Screen is roughly 4" x 10" so I have 40 square inches, should be right on for my feeding rate (3.5 cube equivalents). The CLFs are standard-issue 2700k 23w. So I have 92w total with 46w on each side. Run 8 hours on/16 off opposite main tank lighting. So basically I'm using the "high intensity lighting" update, since it mentions being better for promoting green growth.

... I have 50 gph per inch, which is above the suggestion of 35 gph/in, but again the guideline mentions more flow being better if you're getting spongy yellow growth instead of green growth.

Wille, thanks for the pics. I too would like to see the reflectors while they are installed.

One of the things that I missed in the Basics update was related to the double-lit screen: the caveat to this rule is that all of the light must be directed at the screen, which means your reflector needs to be very efficient. With your setup, it looks like the CFLs might not be quite as close as they can be, the 23W lamps aren't as intense as say 42W so you can get them a little closer when they're sideways, so you might want to look at that.

I'm guessing that the lamps are arranged like they were for the larger screen, and you cut them down (EDIT: you cut the screen down) and left them roughly where they are, and turned the reflectors. Am I right? The problem is like I stated above that you are going to have a difficult time getting the light from the sides and back of the lamps, which are positioned near the edges of the screen, to get directed towards the center of the screen. Basically you're losing a lot of intensity because of the width of the screen in relation to the position of the lamps, even with reflectors. If the reflectors are pointed to the center of the screen, that would mean that the light is directed at an incident angle to the screen, and in theory, this should be fine, since you're running extra wattage, but I think it's pushing the envelope for considering it a double-wattage system for that reason.

You're about right on the double-lit rule (just got the e-mail where you point this out) but if your reflectors aren't quite right, you might have to adjust the feeding or on/off time to compensate a little, and of course this all comes down to GETTING the green algae in the first place :headwally: which we all haven't been able to figure out with you...

One solution here is to up the photoperiod, maybe to 12 or 14 hours to make up for lost intensity due to distance and angle of the lights. Another solution is to use one single 42W CFL on each side with a reflector that directs the light on a perpendicular to the screen, and that is sized to fit the dimensions of the screen more exactly.

I don't think your problem not growing green is related to lack of the correct type of algae in the system, but I'm not ruling it out. So I say go for it if you think it will make a difference, it can't hurt anything, I just wouldn't expect it to be the solution. I think your problem is intensity and photoperiod.

On a side note, I have noticed on my system that I am growing a lot of the yellow gooey stuff and messing with the photoperiod hasn't seemed to change very much, but my screen is still oversized as well. When first started the system, I got awesome green growth for months. When I moved the entire setup, and let the tank go without the scrubber for a week (on 2 separate occasions) the first few weeks to months of growth were awesome, and on each instance (move) the growth slowly progressed to a less green, more yellow type of growth. After the second move I trimmed the screen down at the same time, just to clarify. I am also locked into T5HOs for the lamp length so I lost a little effective intensity by trimming down from 20" wide to 14". But anyways, my point is that it might be possible that as you run a scrubber longer on a tank that has history without one (an established tank), it will take some time to suck out all of the N and P in the rock and substrate, and when that's gone, you are left with an even more oversized scrubber than is required.

I'm waxing a little philosophic here, but I think there is a point to be made with respect to Wille's tank - it has no history at all behind it, there's no N and P soaked into the rock for the scrubber to pull out on startup, so you may have skipped over the progression stage that I have seen and are now it a "food in, algae out" direct relationship. I might have to run this by a few others elsewhere to see if it makes any sense, right now it's just rolling around in my head. It makes sense to me because people that have nasty rock generally need a good 6 months of powerful scrubbing to get past the initial brown/black stages and into the green stage. The natural progression, all other factors being equal (feeding, no trapped dead fish, etc) is that the algae will eventually 'use up' all of the last remaining nutrients is needs to grow at the level it was before, and ends up going yellow. The solution would seem to be that you would start heavy feeding, or downsize the scrubber even further. If this ends up being the case, that means even the current feeding/sizing guideline would be too big for the long term, which would mean these systems are even better that we all thought.

 

[der_wille_zur_macht]

Thanks for the feedback. For the record, the lamps are much closer than they look. The pipe is actually not perfectly centered over the sump thanks to a lazy plumbing job. On one side of the screen the lights are about 2.5" away, and on the other about 3.5". Also, it's not obvious, but the two CFLs on each side are practically touching each other - there's about a half inch gap between them. I think having taken this photo on my cellphone at a weird angle has skewed the appearance of the dimensions a little.

I'll see about getting a reflector photo but it will be awkward at best with them installed. The way the whole thing is nested down inside the sump makes photography tough considering the sump is not transparent. Though, having spent a significant portion of my reefkeeping hobby studying light, I'd say I'm fairly confident that they're effective. Plus as mentioned above, the inside of the sump is gloss white, so there's probably much better "passive" reflection than in most systems. My longterm thought is to switch to DIY LEDs but I had wanted to nail the scrubber with CFLs first to "get the hang of it" before going down a path that's less traveled.

I will lengthen the photoperiod a bit and see what happens. I'm also probably going to try to get a "seed" of algae from another tank, though I'm with you all on being unsure if that will be effective, or even on the best way to do it. I can't imagine that rubbing a tiny bit on the screen will really accomplish anything besides just immediately washing it all into the tank at large where it'll probably get gobbled up by the cleanup crew or blenny. Maybe I can convince a local reefer with an algae problem to let me leave a screen in their sump for a week or two, letting it get grown over with algae, then ziptie it to my screen or just replace my screen with the seeded screen. At least this way the algae would be "captive" on the screen.

 

[Floyd R Turbo]

You can get tufts of GHA and tie them onto the screen with fishing line. I know that when I pull them out of a non-scrubbed tank (or off my scrubber), these tufts are next to impossible to break without a scissors or knife.

 

[Floyd R Turbo]

Also I just looked at your lights again and I see what you mean. One other thing is that with the lights being so close together, you are getting a lot of light going between the lamps and losing that, as well as the quadrant of each lamp from their closest points around to the back, which would be next to impossible to get routed around to the front without a reflector that separated them from 'seeing' each other, if I am envisioning this right. The reflector you would need to use in order to get the most out of the CFL and truly utilize the double-intensity rule would be one that wraps around the entire lamp as in the last pic in post #3257. If you are losing any light sideways, you can't use that rule.

 

[der_wille_zur_macht]

Have any ideas of the PAR that should be expected on the screen for the "normal" approach vs the "high intensity" approach? I have a friend with a PAR meter - getting numbers would end any armchair speculation (on my part or yours).

 

[TheAquatect]

I have to say, reading through this thread was a really interesting time for me. I am new to SW but the concepts you are working on applying here are typical of the Walstad method for FW tanks. Having done that for a few years, I like what I am seeing. Plants are the ultimate filters, except under extreme conditions where metal or chemical toxicity hinder growth or kill them.
I noticed a preference toward double lights on a single screen for algae growth and I am wondering if there is any know issue with screen on either side of a light? My though being it is cheaper to double your growth area with screens than with lights?

I am currently working on an ATS design for my new tank and was already able to shorten its length based on the work and info already supplied here so great work so far guys!

 

[srusso]

I see green algae... Maybe not on the scrubber but it's algae and it's green. I know for sure algae "supply" is not the issue. I know your not arguing, we will get yours working like all others have... Let's see those DIY reflectors and then make our final suggestions.

 

[srusso]

Having another look at your tank and I just realized I think I have read through your tank build a long time ago, Plywood tank! Read the whole thing, excellent build by the way!!

 

[srusso]

I have to say, reading through this thread was a really interesting time for me. I am new to SW but the concepts you are working on applying here are typical of the Walstad method for FW tanks. Having done that for a few years, I like what I am seeing. Plants are the ultimate filters, except under extreme conditions where metal or chemical toxicity hinder growth or kill them.
I noticed a preference toward double lights on a single screen for algae growth and I am wondering if there is any know issue with screen on either side of a light? My though being it is cheaper to double your growth area with screens than with lights?

I am currently working on an ATS design for my new tank and was already able to shorten its length based on the work and info already supplied here so great work so far guys!

I came from the same world, Low tech/ no tech planted tanks were a lot of fun, almost zero work to keep running once it's setup and established. Same reason I came to algae scrubbers, looking for the SW equivalent.

If you have never built one my best suggestion is build it as close as you can to the already defined specs. It will save you the money and headaches... Once you have one running well and you have learned how to "dial" it into the sweet spot, then modify it from there if you still feel you need to...

 

[srusso]

Thanks for the feedback. For the record, the lamps are much closer than they look. The pipe is actually not perfectly centered over the sump thanks to a lazy plumbing job. On one side of the screen the lights are about 2.5" away, and on the other about 3.5". Also, it's not obvious, but the two CFLs on each side are practically touching each other - there's about a half inch gap between them. I think having taken this photo on my cellphone at a weird angle has skewed the appearance of the dimensions a little.

I'll see about getting a reflector photo but it will be awkward at best with them installed. The way the whole thing is nested down inside the sump makes photography tough considering the sump is not transparent. Though, having spent a significant portion of my reefkeeping hobby studying light, I'd say I'm fairly confident that they're effective. Plus as mentioned above, the inside of the sump is gloss white, so there's probably much better "passive" reflection than in most systems. My longterm thought is to switch to DIY LEDs but I had wanted to nail the scrubber with CFLs first to "get the hang of it" before going down a path that's less traveled.

I will lengthen the photoperiod a bit and see what happens. I'm also probably going to try to get a "seed" of algae from another tank, though I'm with you all on being unsure if that will be effective, or even on the best way to do it. I can't imagine that rubbing a tiny bit on the screen will really accomplish anything besides just immediately washing it all into the tank at large where it'll probably get gobbled up by the cleanup crew or blenny. Maybe I can convince a local reefer with an algae problem to let me leave a screen in their sump for a week or two, letting it get grown over with algae, then ziptie it to my screen or just replace my screen with the seeded screen. At least this way the algae would be "captive" on the screen.

Sorry I am very very trained to never ever add algae from one tank to another... One word "Bryopsis" all it takes is one spore to take hold... The nightmare I have been dealing with is enough to make you crazy.

 

[der_wille_zur_macht]

I see green algae...

FWIW, what you're seeing there is just slimy green cyanobacteria, not algae. Flecks of it show up on the scrubber if it's left for more than a week between cleanings but clearly this is not the hairy "green algae" in all the photos of scrubbers that people seem to consider effective.