Algae Scrubber Basics

[maglofster]

The end should be capped, all flow should be going through the slot. If you feed the ATS with water from the overflow of the DT it's wise not to cap the end but instead put an elbow pointed uppwards and add a piece of tubing straight up, this will serve as an emergency overflow should the slot become clogged.

 

[parrotchute]

Thanks, will do. I've got a pump (mag 7) for it.

 

[salty joe]

:wavehand: :thumbsup::frog:

 

[Floyd R Turbo]

The end should be capped, all flow should be going through the slot. If you feed the ATS with water from the overflow of the DT it's wise not to cap the end but instead put an elbow pointed uppwards and add a piece of tubing straight up, this will serve as an emergency overflow should the slot become clogged.

I would not do this. One of the concepts is that when you cut a slot straight and of the correct width, and insert the screen into it, if algae tries to grow into the slot, then pressure will build up or the flow will be shifted to another part of the slot. Over time, this will balance out and eventually the pressure will increase at the slot and this will force the algae to stop growing (too much pressure). For this to work right, you need a water column available to perform the pressure. Providing a 'relief' flow option will only allow the algae to grow into and completely block the slot and all the flow will go out the bypass / emergency flow.

I did exactly this on my first build and within a few days, I got flow through the bypass, and I had it terminated underwater so it created a siphon and cut the flow to the screen down to about 20% at best. I ended up capping it and letting the water level build up in the overflow to create pressure.

So slot clogging due to algae growth is really not the concern, as this would happen very slowly and not all at once. What is of concern is the pipe clogging, but this is an issue that can happen with any overflow pipe, like a snail getting in the pipe and stopping flow at some point. This is why most people put a screen over the intake in the overflow box, or have teeth on their overflow, or use a Herbie or BeanAnimal.

I will make a comment that while some choose to insert their screen into the slot tube rather far into the pipe, I choose and recommend that you only insert it about 2x the thickness of the pipe wall. This allows anything large to get shoved to the end of the slot tube rather than being caught at the start of it.

One design I have seen has the screen inserted into the pipe far enough that it touches the top inside of the slot pipe, then it was held by just one zip tie in the middle. This is fine as long as your pipe is well protected at the intake (tank side) but I still wouldn't do it. I don't see any benefit.

 

[scolley]

Just ignore the nay sayers, report your personal results, and experiences building/operating ATS's .

Got it. Here goes...

Here's the results of my 1st 3 weeks under XR-E LEDs on my 29g. Scraped off about 1/5 of a cup of green stinky. Salifert kits report 1.5 PPM Nitrate, 0 PPM Phosphate.

I spent some time in prior posts here going over detail regarding light cone overlap from the LED optics. Yet I see no evidence in the screen of the known "bright" spots being washed out. So I'm not going to worry about that further. Algae grows on the entire screen.

However the accumulation of dark green to the right side appears to correspond to the somewhat higher water flow on that side. At the pressure/speed I'm running water, it comes out faster on the right side that the water enters the slotted tube from. I assume I can tweak that.

As for any question on LEDs. My prior post linked to the details. Clearly plain ole' Cool White XR-E's can work. I've got a few deep reds that I bought from Mouser that I was going to put in my little LED array. But after seeing this - plus my first ever 0 Phosphate reading in my tank - I'm thinking why bother? It works now.



PS - Those test kit readings were taken 14 hours after a particularly heavy nighttime feeding. So I've got the impression that this setup can keep up with a periodic nutrient pounding.

 

[slow_leak]

I recently read a thread about a skim off show and tell type study comparing cone versus straight skimmers.

I am showing a week of skimming and a week of growth of ATS in these pictures. The side by side shows how I removed biomass of mechanically removed microalgae containing adsorbed nutrients directly and old Euroreef skimmer removing small particulate and DOC from water. Keep in mind scrubber would only have grown more if skimmer was off.

 

[pskelton]

Scolley,

That is impressive growth on the right. Have you checked you actual flow rate? Would be great to see that growth across the entier screen from LEDs. Nice work

 

[scolley]

That is impressive growth on the right. Have you checked you actual flow rate?

Thanks.

And I haven't checked until just now...

About 2 weeks ago I cut the "planned" flow back because the energy consumed by the pump (from my Eheim return) was generating more heat than i liked. So I cut the flow back from my originally planned rate.

At the restricted rate, where the majority of this growth occurred, the flow is 18 gph per inch of screen width. But that is for 1 side only - this is not a 2 sided rig.

So if I were guessing, I'd guess the right side with the thicker growth is getting more like 22-24 where the left is at 12-14.

That said... I could try to fix it with higher flow. But except for looking at this from a purist perspective, I'd have to ask "Why bother?". Right now it's working to the point of stripping Phosphates lower than my Salifert kit can read. Can't do better than that.

IMO it's doing it's job right now. No tweaking should really be needed.

 

[pskelton]

Scolley,
I understand, if it’s working as you need it to why mess with it. The only thing I can say is that from what I have seen no LED scrubber to date comes close to what is being done with T5 and most spiral CFL units. I really would like to see someone optimize an LED scrubber and see that concept fine tuned. LEDs are fairly expensive still especially for experimenting with and the Scrubber community who would take on such a project is small so this is a technology that will likely developed very slowly. What you have achieved so far is good and if you were to continue to optimize what you have started you can bet I will be following along as you update us all on your progress.

 

[scolley]

...The only thing I can say is that from what I have seen no LED scrubber to date comes close to what is being done with T5 and most spiral CFL units...

Yup. Understood. But I'm never going to be that person. I'll never feed my tank enough to really stress an ATS system. I look at some of the algae some ATS's pull out - then look at the size of the tank - and my head spins at the thought of how much food people must be dumping into their tanks to pull that much out. Same goes for skimmers.

During this last three weeks I've dumped exactly twice the food in my tank that I have historically provided it. So I figured it was a good test of the ATS. But my approach to husbandry will never allow me to be someone that stresses an ATS. So...

I've shown simple XR-E's can do an adequate job of growing algae. You could further assume that were I to optimize the flow, I would get even more growth (assuming I provided the nutrients). And beyond that, there's even more light tweaking that could be done.

My two real objectives here appear to be accomplished:

1. Create an ATS that can keep N&P low in my little reef
2. Prove that a very simple LED array can work in an ATS

But I'll be happy to post updates as I go.

 

[papawheelie]

O.K. So after struggling with No3 and Po4, Vodka Dosing, Multiple water changes and whatever else I could think of weren't doing anything for me. My Nitrates were still at 30, and Phosphates at 1. I decided two weeks ago to try an ATS, after reading this entire thread (wow) and so far, so good. My No3 is at about 10 and Po4 are .25. Very happy with the results so far. I will get pictures on here as soon as I figure out how.

 

[srusso]

O.K. So after struggling with No3 and Po4, Vodka Dosing, Multiple water changes and whatever else I could think of weren't doing anything for me. My Nitrates were still at 30, and Phosphates at 1. I decided two weeks ago to try an ATS, after reading this entire thread (wow) and so far, so good. My No3 is at about 10 and Po4 are .25. Very happy with the results so far. I will get pictures on here as soon as I figure out how.

Thanks for taking the time to read the entire thread. Can't wait to see your design. How long has it been running? What are your scrubber and tank specs?

 

[dogstar74]

I would not do this. One of the concepts is that when you cut a slot straight and of the correct width, and insert the screen into it, if algae tries to grow into the slot, then pressure will build up or the flow will be shifted to another part of the slot. Over time, this will balance out and eventually the pressure will increase at the slot and this will force the algae to stop growing (too much pressure). For this to work right, you need a water column available to perform the pressure. Providing a 'relief' flow option will only allow the algae to grow into and completely block the slot and all the flow will go out the bypass / emergency flow.

I did exactly this on my first build and within a few days, I got flow through the bypass, and I had it terminated underwater so it created a siphon and cut the flow to the screen down to about 20% at best. I ended up capping it and letting the water level build up in the overflow to create pressure.

So slot clogging due to algae growth is really not the concern, as this would happen very slowly and not all at once. What is of concern is the pipe clogging, but this is an issue that can happen with any overflow pipe, like a snail getting in the pipe and stopping flow at some point. This is why most people put a screen over the intake in the overflow box, or have teeth on their overflow, or use a Herbie or BeanAnimal.

I will make a comment that while some choose to insert their screen into the slot tube rather far into the pipe, I choose and recommend that you only insert it about 2x the thickness of the pipe wall. This allows anything large to get shoved to the end of the slot tube rather than being caught at the start of it.

One design I have seen has the screen inserted into the pipe far enough that it touches the top inside of the slot pipe, then it was held by just one zip tie in the middle. This is fine as long as your pipe is well protected at the intake (tank side) but I still wouldn't do it. I don't see any benefit.

I've been trying to avoid this issue for a long time. I really wanted to see what the experience of others had to say on this issue, but I've got to say, I can't disagree with you more on this Floyd.

ANYTHING that causes a backup of water, or a water column etc., is just asking for a flood. The return to the sump must be unrestricted. That is why I would advise always to run the ATS with a second pump and not from the drain line. If you have to run it off the drain line or choose to run it off the drain line, then having a pressure relief like Magolfster pointed out is the only way to do it safely. If algae is building up in the slot, then more frequent cleanings are the only way to avoid that or shielding light from the screen.

I feel letting pressure build up to the point of blasting algae out of the way is folly and will ultimately result in an overflow. No doubt while the owner is away on vacation and the neighbor is watching the tank. :uhoh2:

I've been with you on every other empassioned issue, but this is where we must agree to disagree on this. I feel your design that includes allowing a water column to back up so that pressure is used to stifle algal growth is inviting disaster.

Respectfully,
Aaron

 

[Floyd R Turbo]

I know what you're saying, as it was a concern of mine as well. The solution to preventing the slot from clogging due to algae growth is not to provide a secondary bypass mechanism however, the solution is to block the light from hitting the slot/screen point and prevent the issue in the first place. The bypass will eventually take over and drop flow to the screen, sometimes cutting it off completely.

The pressure solution works. The only time I have ever heard of a flood occurring is due to a drain clogging in an enclosed box system after letting it grow for 2 weeks (it was an experiment), resulting in a big chunk of algae detaching due to weight, which is one reason why a 7 day cleaning cycle is recommended. Algae grows somewhat exponentially, so waiting that extra few days really amps up the growth.

As for when the neighbor is watching the tank, that is a good example and would be reason to add the bypass, but with a valve on it so you could open it up when you're gone as a precaution.

I can see where your concern comes from, but you have to remember that the slot does not clog all at once and suddenly, it takes time and it does reach a critical point where the algae cannot grow any further into the slot. It is like a self-regulating control system, and it works exactly that way.

I have no problem with adding a bypass, just make sure that it takes a turn up as high up in the sump cabinet as possible then a double-90 over and down, and doesn't terminate underwater (to prevent siphon). Or preferably, you would want to do a 90 to horizontal, then a tee with one end sticking up (open) and the other down through a pipe that could then terminate underwater. This could be done before or after the slot tube. After would maximize flow to the slot and allow for backpressure to build on either end of the slot, so that would be the preferred option.

 

[Enjoy]

Here are a few quick pics of my new ATS setup. Screen is oversized right now, so I will be cutting it down a bit. I also need to bump up the flow rate a tad.
These pictures are 4 days after setting it up, but with today being day 16 there is brown algae covering the screen. I will continue with my weekly cleanings and post updates here.

Let me know if you see anything that I can improve.
Thanks

3/4" drain w/ uniseal in bottom....

Lights are about 3-1/2" away from screen on each side. It is oversized for this system and you can see spotlighting in the center.

I will post new pictures later with some algae growth.
Thanks :wavehand:

 

[scott26]

Nice scrubber Enjoy! I like how it is enclosed.

 

[Floyd R Turbo]

scolley, in this pic, I see a couple of silver-dollar shaped bald spots (that have grown back). Those are usually the result of a 'black algae' (which is really a very dark slime) that lets go. It is a sign of a very high nutrient system, what happens is that the really dark/black algae blocks light to the 'roots' underneath and they lose strength and detach. The solution is to clean the screen very well every 3 days so that the dark algae is gone, and doesn't block light to the lower layers. Also it helps to dial back the flow a little bit so that the black algae doesn't tear away.

Still, you're having success it sounds. Keep it up. Watch the screen for the changover from the slime to hair algae, and keep it clear of the dark slime. Even if you have to take it out back of the shed and give it a good whoopin.

EDIT: just in case, the 3 days is if you are getting black slimy stuff. If it's more brown, then still 7 days. I looked again and it looks like you have clumpy growth that could be detaching. Until you get a good sheet of hair algae growing consistently I would watch it for bald spots and do a cleaning when you see one, and monkey with the flow rate to keep them at bay. Once you get good consistent thick green hair crank up the flow and clean every 7

 

[scolley]

scolley, in this pic, I see a couple of silver-dollar shaped bald spots (that have grown back). Those are usually the result of a 'black algae' (which is really a very dark slime) that lets go. It is a sign of a very high nutrient system, what happens is that the really dark/black algae blocks light to the 'roots' underneath and they lose strength and detach.

Thanks for the tips! I was wondering what that was.

It was a very dark green slime algae. Stinky to be sure. I find it a little tough to think of my system as high nutrient. Granted, I never tested for Nitrate or Phosphates very often. But that's because I've got virtually zero problem with algae. Tiny traces of hair on my Vortex, and that's it. But when I did test, it's always been low: Nitrates 4 or 5 ppm, Phosphate 0.1 or less typically.

Granted I DID double feedings for three weeks that screen "grew" out. Maybe that's it. But 'twas never a high nutrient system in the past. Hmmm...

So what's the point of trying to get the algae to switch over? What difference does it make, as long as it's pulling nutrients?

Thanks for the help.

 

[Floyd R Turbo]

Yeah I was wondering about that. It didn't make much sense since you had mentioned low nutrients but I saw a similar situation with another scrubber (the bald spots) so I figured I would mention it. I think part of it is the immature screen, and honestly it may be an effect of LEDs, I don't know though. The reason you want the green hair is because it is stronger and 'fluffier' and lets light through to the lower layers much better, which means you can get thicker growth and it stays connected.

Remind me, are you running the screen one-sided or two?

 

[scolley]

It's a one sided system. And I suppose it IS possible to think of my system as high nutrient for the last three weeks while the ATS was running as I simultaneously double fed the tank. But I still kind of doubt it.

As you indicated, it could be an LED thing. Or rather an outcome of the particular LEDs I used, plus the geometry I'm using them in.

Also, FWIW I borrowed a PAR meter, and my screen is getting around 525 PAR on most of it, with hot spots spiking to over 900. Primarily low 500's though.