CW-100 Algae Scrubber Question

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FishyDP

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I have been running the CW-100 on my 150 mixed reef for about a year now. Scrubber light schedule is on 6pm-10am. Using Sicce 2.0 pump on full power. Last couple months algae growth slowed significantly on screen, and turf algae now growing in display.

Cleaned/maintenanced pump and scrubber a few weeks ago, no difference. Could the scrubber lights be losing par? Feeding schedule, bioload, flow have not changed in last year. Display lights and schedule have not been changed either. Corals doing fine. Running Bubble magus curve 7.
 
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vetteguy53081

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The lights run on constant as they are LEDs' and should not lose intensity. Try reversing the schedule and run 10a- 8pm as phyto and chaeto get their nutrients when tank lights are also on. The way youre running it may assist with PH control but that would be about it. Turf Scrubbers use algae as a natural water filter to remove nitrate, phosphate, and other pollutants from your aquarium water. Rather than having algae grow uncontrolled inside your display tank, an algae scrubber allows you to grow algae in a controlled setting where it can be easily removed—thereby removing contaminants from your tank in the process.
As algae begins to grow on the screen, it “scrubs” your aquarium water of excess nutrients—so you’ll have less algae growing inside your tank. Once the screen is covered in algae, you “harvest” it by removing a sizable portion, thereby removing the contaminants that fueled its growth from your system.
As for algae in your tank, be sure to clean unit and remove mat of algae every 7 to 21 days, or when it is black, or when it fills up the scrubber.
Is your tank at or near a window?
 

vetteguy53081

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The way I clean mine is removing the screen and removing the algae that was harvested and scrubbing the screen with a toothbrush followed by a good rinse. Make sure you get the outlet where water comes out cleaned well as it could restrict bith the flow and production of algae
 
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My tank does not get any direct sunlight. I was cleaning the screen every 7-10 days, that was about how long it took for the screen to fill up really thick with algae, and start to restrict flow. I remove the screen, and scrape about 90% of the algae off with a credit card. That way there is some left over to grow more algae.

I like having some algae as part of a healthy system, and the cw-100 was doing a really good job keeping it in the scrubber until recenty. I will reverse the light schedule and see how that goes, thanks. My algae has never turned black, I will keep an eye out for that too. I also clean out the inlet every time I clean the screen.
 
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I suggest that detachment issues or “sloughing” is due to the algae left on the screen. This can be made worse if you aren’t rinsing with freshwater to get rid of heterotrophic bacteria species that feed on algae, especially in thick mats that are hardly/not lit near the screen. Algal procession must repeatedly be interrupted on screens otherwise other species will eventually take over.
 
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I have not been rinsing the screen. This sounds likely to be a part of the issue, and makes sense that the algae eating bacteria has reached higher levels slowing algae growth.

How much of the algae would you recommend removing from the screen during harvest and before rinsing with fresh water?
 

Turbo's Aquatics

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Are you rinsing it?

I have not been rinsing the screen.
Good catch @Garf. Scrape with plastic scraper or credit card then rinse under room temperature, gently running tap water. Scrub the top edge of the screen with a stiff brush (I use a grout & tile brush) and scrub the slot as well. If you have light blockers, clean the growth off the tips also
 
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Rinsed screen and reversed lighting schedule. This worked great, have a full screen of algae again. Only issue is that I do not have any algae filtering the tank for several days after harvesting. Upgrading to 230g may get a 2nd scrubber and alternate cleaning schedule.
 

atoll

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I hardly ever rinse my screen, if there is a small amount of slime I just brush it off. I also give my Ulva intestinalis that I grow on my screen a haircut by trimming back the Ulva to around 1" so we don't start from scratch. Been doing this for about 2 years now and it works well for me. I never understood removing all the algae on the screen and more or less starting from scratch.
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Turbo's Aquatics

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Rinsed screen and reversed lighting schedule. This worked great, have a full screen of algae again. Only issue is that I do not have any algae filtering the tank for several days after harvesting. Upgrading to 230g may get a 2nd scrubber and alternate cleaning schedule.
Someone actually ran a series of tests on their scrubber (I think it was a DIY) where they tested the water every 6 hours or so before and after a harvest for several days and they didn't see a significant spike in nutrients.

If you are worried about that though, leave 25% of the algae on the screen. IMO the best way to do this is don't use a scraper to remove the growth, or at least not the wide flat edge of one. Use the corner and scrape in an "X" pattern on one side, and a "#" pattern on the other. You will have areas where the screen is exposed on both sides where those patterns intersect. Also you can try just pulling off handfuls with your fingertips, this might be enough without scraping.
Then scrub the top edge (where the screen is in the slot) and rinse.
 

Garf

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I hardly ever rinse my screen, if there is a small amount of slime I just brush it off. I also give my Ulva intestinalis that I grow on my screen a haircut by trimming back the Ulva to around 1" so we don't start from scratch. Been doing this for about 2 years now and it works well for me. I never understood removing all the algae on the screen and more or less starting from scratch.
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20201130_112640.jpg
20200924_113613.jpg
technically this is not a turf scrubber, but if it works, it works :)
 
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Garf

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It's an algae scrubber in that case although there is also the odd small patch of shirt bot long turf here and there.
For turf you need to interrupt the normal algal procession, ie freshwater rinse. Primary colonisers eventually get suffocated.
I seem to remember your username on Santa Monica’s site, many years ago. Is that you ? :)
 

atoll

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For turf you need to interrupt the normal algal procession, ie freshwater rinse. Primary colonisers eventually get suffocated.
I seem to remember your username on Santa Monica’s site, many years ago. Is that you ? :)
I dont wish to grow turf I find growing Ulva better and have been doing so for a number of years. Ulva grows faster IME and my tangs and fox face love it.
I have been on the SM site but haven't been on there for a while.
 

KleineVampir

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I have also ran into scrubbers not scrubbing... first of all I think your photo-period is way too short. If I were you I'd probably go from 4pm-12pm or something like that. Not sure how long your particular unit is meant to run, but if it's like other scrubbers I'd say 20 hours is the way to go. I mean some people run them 24/7/365 but some algae scrubbers run too hot for that.

You have to keep in mind that the light on the scrubber has to out-compete the lights of your display. So sure at first there were enough nutrients to grow it in your scrubber and your display, but now it's one or the other and one of them is going to win. And the goal is to make sure the scrubber is the better environment for algae growth!
 

KleineVampir

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Also it occurred to me that your scrubber pulls phosphate out of the water, and in turn out of the rocks. This can actually turbo-charge the algae on the rocks. And maybe shift the balance in the rock-algae's favor. Not sure exactly what to do about that, except harvest the algae on the rocks and hope that all the phosphate can be taken out eventually.
 

Turbo's Aquatics

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Basically, what can happen over time when you start out with "clean" live rock (i.e. virgin/dry rock or fulled cured/cooked live rock) is that rock can act like a sponge for waste. Under certain conditions, phosphate (along with calcium) can deposit in crystalline form on the rock. So there can be both a "soft" and a "hard" form of phosphate bound to the rock (those are terms I'm just using for simplicity).

It's not exactly true to say that when the phosphate in the rock is lower than the water, that phosphate is absorbed by the rock, but it's an easy way to think about it. The converse is more accurate: when the rock has a lot of bound phosphate and the water column phosphate is low, that's when the phosphate gets liberated from the rock. The "soft" phosphate more easily, the "hard" phosphate is slower.

Bacteria and algae work together to liberate phosphate. So when you have that happening, and light and water flow available, you get algae growth on the rocks. This is not atypical when someone adds a scrubber to the system. This generally is an indication that your rock is saturated with waste, or at least has some waste built up in it over time.

What you want to do in this scenario is maximize the scrubber, minimize the DT. The bacteria will still liberate the phosphate. So make sure you're not over-lighting your DT, and get your scrubber ramped up and working as it's optimal capacity for your system. In a system with a lot of built up waste, it can take 6-12 months before algae stops growing on the rock. I've seen many examples of this cycle taking place.
 
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