My first led algae scrubber

[Skinnysloth]

Time for a long overdue update. Last time I posted, I added a blue led to one side of the screen and this is the results.

2 weeks growth, blue and red side:

2 weeks growth, red side:

As you can see, there was a little bit more growth on the side with the blue. Nothing surprising, since other people have seen a similar result when they added some blue to their red leds.

 

[Skinnysloth]

Now, in the meantime, I’ve made the screen wider as I had more room to do so. Also, even though my screen was grossly oversized (effectively 6”x8” for feeding only 1-2 cubes a day), I wasn’t getting the algae reduction in my DT as I wanted, so now it’s 8”x8” with still only 1-2 cubes a day. I also upgraded my return pump from an Ocean Runner 3500, measured return flow of about 300gph, to a Laguna Max-flo 2900, giving me an estimate flow of around 700gph or so (haven’t actually measured it). In my new setup, I’m feeding the scrubber about 300-400gph.

I also changed the all red side of my led lighting with a new blue/red/violet (405nm) setup.

And the results:

2 weeks growth blue/red side:

2 weeks growth blue/red/violet

Side view:

So, I expected the new side to produce more algae given that it’s more efficient with light production, but it actually grew less. This may have been explained by the fact that there was less water flow on that side (red/blue/violet) of the screen. Given slightly more light/similar light, the side with more water flow will give you more algae growth. As you can see, there was a lot more growth with my new setup. I’m quite satisfied with the growth, now I just have to wait until the DT’s algae dies off.

 

[widmer]

I just came across this - Excellent thread! I've been playing with LEDs for a few years now, and more recently built a terrestrial plant light (for my kitchen herbs), using the 660 reds, 455 blues, but also added a couple full-spectrum ("cree xp-g neutral") whites. The whites were added for 2 reasons: 1) articles I have read suggest that plants will use various wavelengths as cues for metabolic processes separate from photosynthesis, so I added the whites to essentially "fill in the gaps" between the two photosynthetically active colors, and 2) if you add a couple whites it's more aesthetically-pleasing because you can actually see the color of the plants again.

For my next ATS in the works, I was planning to simply use a combination of the 660 reds + white LEDs in something like a 3:1 ratio. It was great to see your documentation of results here. Keep the pics coming as the system evolves!

 

[SantaMonica]

Keep in mind when measuring the volume of growth in a cup, that greener growth may not hold onto water as much as darker slime growth, and thus may appear to be less (and will certainly weigh less).

 

[Skinnysloth]

Keep in mind when measuring the volume of growth in a cup, that greener growth may not hold onto water as much as darker slime growth, and thus may appear to be less (and will certainly weigh less).

Ah good to know and another reason why the red/blue/violet side had 'less' mass to them.

The screen above also illustrates another common problem some people can get with scrubbers. You'll notice the top half is a lighter green and the bottom half, a darker slime green. This is due to a design/space limitations where I can only effectively light the top half with direct light, the bottom half gets incidental light. I needed the screen to be that long so it'll reach the water line in the sump to prevent noise from water coming off the screen. So, long winded way to say, if you consistently get dark slime growth, you may need to increase the light intensity or flow, or even both.

@widmer
Thanks for the compliment, I will surely keep the pictures coming when there's something worthwhile to post.

That's really interesting regarding plants using other wavelengths for non-photosynthesis metabolism. It makes sense that plants would evolve to use more than that just the red and blue blue spectrum of light. I'm sure other wavelengths are used to initiate different non-photosynthetic, even non-metabolic processes. I look forward to your new ats build and results.

 

[Floyd R Turbo]

Your flow increase certainly had something t do with it. What I have found is that when you are running LEDs, you have much less propensity to get yellow growth compared to CFL. So you can run the photoperiod longer before you get yellow. And, from what you have seen, if you increase the flow significantly, and couple this with more LED power, you don't burn the algae - you get a significant amplification in growth.

great pics and documentation. If you don't mind, whenever I get around to doing my next "Algae Scrubber Basics" writeup, I might use a few of these pics.

 

[knight2255]

skinnysloth, do you use saran wrap?

 

[Skinnysloth]

@Floyd I would be excited to have you use my pictures in your next writeup.

@Knight I did not use any saran wrap.

As an added note, the latest 2 weeks growth pictures on the 8"x15" (effectively 8"x8") was from a relatively new screen. I made the screen, roughed it up and threw it in the sump for 3-4 days to 'seed' it. When I had finished the new red/blue/violet leds, I installed the new screen.

 

[fyrfytr]

Keeping an eye on this, looks like something I may want to look into

 

[zland1]

Any updated tank shots?

 

[6lilfish]

Where are the close up shots and did you clean the glass. Very nice Algea scrubber thanks for the pics of it Im thinking abouit one on my new tank

 

[Skinnysloth]

No updated full tank shot as it hasn't changed all that much since I last posted one. I had to re-dip my acan and frogspawn in hydrogen peroxide again as the algae was encroaching on the corals, but other than that, everything had remained pretty much unchanged.

While reading this thread: http://www.reefcentral.com/forums/showthread.php?t=2251271 a light bulb went off in my head. Someone may have already posted something similar, but sometimes my mind ignores the simple things. Ever since this tank had been setup, I've never cleaned/siphon the substrate. I had snails, bristle worms and a goby that would agitate the sand, but ever since my goby decided to go cliff diving out of the tank, the algae really started to grow on the sand. In the thread mentioned above, it was estimated that an one inch sand bed takes about a year to fully saturate with phosphates and it was around that time, that I noticed more algae in the display tank. My clean up crew would take care of the small patches and I never gave it a second thought. Fast forward another year and this is probably why my tank is in such a sad state with relatively little change despite great growth with the algae scrubber. The scrubber is not able to keep up with all the phosphates trapped in the sand/live rock. I will need to clean and/or replace my sand before the scrubber or any other phosphate removal method will make a dent on my algae problem.

I knew I had a nutrient export issue, but wasn't quite sure about origin of the problem. Now, hopefully, I can clean the substrate without the tank crashing. Since the deepest is about two inches, I assume I'm mostly safe with regards to siphoning it. To be on the safe side, I'll probably clean small sections at a time, so if any noxious gas escapes, it won't overwhelm the tank. So, the lesson of the day is when a problem presents itself, start with the basics first, and only after exhausting those possibilities, then look at the more exotic explanations.

So after I clean the sand, I hope to provide more substantial full tank shots to document the results of the scrubber.

 

[salty joe]

I will need to clean and/or replace my sand before the scrubber or any other phosphate removal method will make a dent on my algae problem.

I clean the sand, I hope to provide more substantial full tank shots to document the results of the scrubber.

It's common knowledge that calcium carbonate takes on phosphate and I have heard that arragonite sand is the problem. But what about the rock we use? If the sand is taking on P, then is not the rock as well?

Another problem I have with that aproach is once you get to the point that sand or rock is no longer taking on P and is at a point of equillibriam concerning P, what would be the difference between that and having no sand or rock whatsoever?

I can't remember where, but I have read posts saying the excess P leached to a point of equilibriam within a matter of months of bringing the P in the water down to an acceptable level. Which makes sense to me.

IDK though.

 

[Skinnysloth]

It's common knowledge that calcium carbonate takes on phosphate and I have heard that arragonite sand is the problem. But what about the rock we use? If the sand is taking on P, then is not the rock as well?

Another problem I have with that aproach is once you get to the point that sand or rock is no longer taking on P and is at a point of equillibriam concerning P, what would be the difference between that and having no sand or rock whatsoever?

I can't remember where, but I have read posts saying the excess P leached to a point of equilibriam within a matter of months of bringing the P in the water down to an acceptable level. Which makes sense to me.

IDK though.

Absolutely the rocks are absorbing phosphates, but if I can bring the amount of stored phosphates down by cleaning/replacing the sand, it'll allow the scrubber or any other forms of phosphate removal, to produce visual impact more quickly.

Regarding phosphate, once it reaches the equilibrium point, there probably is no difference at that state with having no rocks or sand. But if you start off with no rocks or sand, you'll reach that point a lot quicker. Also, as far as I know, rocks and sand still provide a place for denitrifying bacteria to exist, but I don't think that was the point of your post (bare bottom/no rocks vs sand and rocks). What I'm trying to do is move my phosphate absorber from the rocks and sand to the scrubber to allow easier export of phosphate. From what I've read, a scrubber is a more efficient means of phosphate exportation than nitrates that some people get to a point where they have an imbalance of P to N ratio. As a result, some feed more to introduce more phosphate into the system to allow the uptake of nitrates. I would like to get to that point, so the excess bounded phosphate would leach out of the rocks and be removed via the scrubber.

I'm pretty sure if I tested my water right now, phosphates would be at an acceptable level, but that does not mean my phosphate issue is gone. It's still in the system bounded to rocks, sand, etc. as painfully illustrated by the abundance of algae in my tank. I'm not adverse to living with algae, I just prefer it grow on my scrubber instead of my display tank. I've had chaeto in my sump previously and it grew tremendously. Every month I had a grocery bag of that stuff that I threw away. For whatever reason, it stopped growing like mad and I started to get algae/cyano in the display tank. Perhaps it was at this point that the sand and rocks stopped absorbing phosphate and the chaeto couldn't keep up. The chaeto was probably not growing and dying because the hair algae was so much more efficient at absorbing the extra phosphates.

 

[salty joe]

Your mentioning imbalances reminds me-I have read of potassium depletion due to algae growth. I wonder if that could have been the cause of the Chaeto decline? Might be worth checking and maintaining NSW levels of potassium.

In any event, really good thread-thanks for sharing.

 

[Kawi9_cf]

I'm thinking your gonna have to change the sand out completely. It will be really hard to get the sand perfectly clean in the tank.

 

[Skinnysloth]

Yeah, I have considered getting a potassium test kit and dosing the appropriate amount. The potential depletion of potassium due to the overgrowth of hair algae could have starved out the chaeto. Perhaps hair algae is also more efficient with potassium uptake as well, hadn't thought of that, but it makes sense. Especially considering, during the algae outbreak, I didn't do as many water changes that would normally replenish the potassium. It probably wouldn't matter as the hair algae would continue to exponentially outgrow the chaeto and uptake all the extra potassium anyways.

@Kawi9_cf Yeah, I was kind of preparing for a complete change out. I just don't want to make any huge changes all at once. I'll clean it first and may do small frequent change outs. Don't want to get rid of a large amount of nitrifying bacteria all at once.

 

[SantaMonica]

But what about the rock we use? If the sand is taking on P, then is not the rock as well?

Yes, same.

once you get to the point that sand or rock is no longer taking on P and is at a point of equillibriam concerning P, what would be the difference between that and having no sand or rock whatsoever?

Removing the rock/sand at that moment would export the P.

From what I've read, a scrubber is a more efficient means of phosphate exportation than nitrates that some people get to a point where they have an imbalance of P to N ratio.

No need to deal with this. Zero is not "zero"; there is still plenty of N or P in the system for scrubber growth.

I'm thinking your gonna have to change the sand out completely

Naw. The stuff that attaches to the sand particles is used/removed naturally based on the algal export. Including metals.

 

[TY31088]

SS,
How's the tank? Read the entire thread today.

 

[Skinnysloth]

SS,
How's the tank? Read the entire thread today.

Well, it's been six months with marginal improvement. The DT is still an algae farm even with a decent amount of harvest from the ATS weekly. I still manually remove algae from the DT, peroxide dip the corals when it starts to get over run with algae, and do 20% water changes per month. My rocks and sand may have had absorb so much phosphate that the ATS hasn't been able to catch up. My filtration consists of the ATS, protein skimmer and activated carbon. I may have to do something more drastic to get this problem to go away, but in the mean time, I'll just continue with what I've been doing.

Possible future interventions I might try include: lanthanum chloride reactor, just enough to let the ATS catch up or a complete replacement of the live rock and sand.