algae scrubber

[wetbehindears]

Iset upba algae scrubber 2 weeks ago I've started growth . basically I'm just wondering if anyone on here uses one and what their experience with it has been positive or negative . I have a basic vertical water fall style I'm currently setting uo a horizontal dump ducket style sense i have the room.

 

[E_rock]

I have consider setting one up. Do you have any pictures?

 

[der_wille_zur_macht]

I had originally planned on using a scrubber as the primary method for nutrient removal on my 360g. It's been running for about 9 months so I don't have a TON of data, but my results have been mixed. My scrubber never really kicked off with solid growth, despite trying a handful of different lighting/flow/size variations as dictated by "standard practice" for scrubbers. I just get a sort of soft green slime (diatoms or cyano). On the one hand, nutrients are not measurable in my system. On the other hand, this annoying greenish-brown slime grows very fast on EVERYTHING in the tank, so clearly the scrubber isn't up to the task of total nutrient control. Luckily this stuff blows off with a turkey baster but I'm getting sick of having to do so this often and am actually thinking about bringing a skimmer in to the mix.

I would not use my experience as a discredit to the concept though, because there are a handful of things about my system that are rather unique (it's very lightly loaded, it was started with more or less sterile rock and sand, etc.). Just, keep in mind that scrubber use is not "mainstream" in the hobby which means you'll be in uncharted territory often.

If you have specific questions lemme know and I'll answer if I can. I don't have any photos of my setup because it's kind of down inside the (opaque) sump and hard to photograph without risking the camera getting wet.

 

[tmz]

I tried a smaller one for a while . It does remove some NO3 and PO4 but not organic carbon. . Not much if any of advantage vs a macro algae refugium ,imo.

It got to be a maintenace issue for me, so I took it off line.
Many are strong proponents for them and some of those overstate what they do. So, if you read the threads about them be careful to sort the wheat from the chaff.
A useful tool for N and P reduction if it's large enough ,seeded with the right algae, well harvested, well lit and flow is managed to suit it.

Really depends on what you feel like trying and your own style.Personally, it seemed to take more effort than other techniques;effort and time that I would rather put into other aspects of the hobby.

If you decide to go with one , let us know about it and how it works for you.

 

[wetbehindears]

K thanks for.replies. i have a small 2x1 foot water fall style. I'm using a skimmer now 4 foot Beckett w mag24 so I'm all set just looking for a.xtra hand in helping my futures
water quality is all.

 

[tmz]

Sounds like a good idea. Have fun with it and good luck.

 

[Gary Majchrzak]

a lit refugium growing macro algae can act as a scrubber, too.

This is what I'm currently running.

 

[der_wille_zur_macht]

I tried a smaller one for a while . It does remove some NO3 and PO4 but not organic carbon. . Not much if any of advantage vs a macro algae refugium ,imo.

The theoretical advantage is space efficiency, a scrubber needs much less volume of algae given the species that grow on a scrubber remove nutrients "faster" than the species typically used in a macro refugium. However once you factor in the light rig, plumbing, and other "stuff" a scrubber needs, the space argument isn't as strong (IME it's hard to make a scrubber that isn't bulky and awkward unless you spend a fair amount of time/money on custom acrylic work).

There are a significant number of people who have run tanks with nothing but scrubbers over the long term, so clearly, they can work. But they're definitely not for everybody.

 

[tmz]

I have not been able to find comparative information on various algae species macro ,turf etc. in terms of nitrogen and phosphate consumption by weight or any other measure or for exudate production. So, I can't comment with cetainty one way or the other on the space saver hypothesis. Please LMK if there is a useful link or reference that would clearly identify not only what algae to use o a scrubber but would also contrast their uptake vs some popular macro algaes like chaetomorpha and calulerpa. .

I agree they can work if sized appropriately and even a smaller one can be a useful part of an N and P management approach but just like a macroalgae refugium they won't remove organics.GAC, resins and skimming do that. ATS algae produce them as do all photosynthetic organisms. Primary target for turf scrubbers is inorganic N and P as I understand it.

 

[tmz]

This cite from the Marine Biology journal by Randy Farley in his article on Phosphate in the Reef Aqaurium gives data for nine types of algae regarding inorganic N and P consumption. I think it would be interesting to compare it to any similar data on the specific algaes used in a scrubber,
I don't have any reason to believe it would be substantially different but it might and if so it should be part of any posit in favor of higher efficiency in N and P reduction with a lesser volume of algae via ats vs a macro algae refugium.


"...For example, Caulerpa racemosa collected off Hawaii contains about 0.08 % phosphorus by dry weight and 5.6% nitrogen. Harvesting 10 grams (dry weight) of this macroalgae from an aquarium would be the equivalent of removing 24 mg of phosphate from the water column. That amount is the equivalent of reducing the phosphate concentration from 0.2 ppm to 0.1 ppm in a 67-gallon aquarium. All of the other species tested gave similar results (plus or minus a factor of two). Interestingly, using the same paper's nitrogen data, this would also be equivalent to reducing the nitrate content by 2.5 grams, or 10 ppm in that same 67-gallon aquarium...."

 

[tmz]

Ok found a benchmark for nitrogen ; nothing to compare for PO4 yet though I still think consumption will be very close for phosphorous too.

"The Reef Aquarium Vol.3", Sprung and Delbeek,pg. 373:

...Algal turf tissue production is 5-20g dry weight pr sqaure meter per day. Algal turf can absorb 0,3 - 1.2 g of nitrogen per day per square meter of screen( Adey and Loveland, 1991). We believe this is a higher figure than an be achieved by Caulerpa ,but it is not known how much higher.."

Well ,we can see how much higher now in view of the Marine Biology Journal assay cited in Randy's article noted above:

For example, Caulerpa racemosa collected off Hawaii contains about 0.08 % phosphorus by dry weight and 5.6% nitrogen.

So for the turf algae in the scrubber it's 1.2g nitrogen for 20g of algae or 6%. For calulerpa it's 5.6%. Not much difference.

 

[der_wille_zur_macht]

Tom, I am not sure you are comparing the correct figures. Rather than just taking into account % of dry weight for a specific nutrient, I think you'd also need to consider growth rate (the blue quote you posted gives it for turf algae) and "density" for lack of a better word (i.e. does a certain screen size of turf algae take up more or less room compared to the same dry weight of caulerpa)?

 

[tmz]

I thought you meant "volume of algae" in which case a gram is a gram.

I think growth rate and density is highly variable in any given system for turf or non turf macro algae. I think alges do vary in their ability to compete for nutrients. It's pretty common to hear observations of caulerpa outcompeting chaetomorpha for example. I've not heard or read similar information on turf algae vs other types though .

Some of the logic in favor of turf algae efficiency goes to the use of other elements in non turf algae for supportive structures etc. ;not to growth rates or density, at least not in the opinions I've read.. I think the significance of a difference if any is overestimated and esily accounted for in the 5.6% vs 6% data contrasted earlier.

I have no idea if certain turf algaes will grow at significantly higher rates or with more density than a particular macroalgae in the same water at the same N and P levels and kept in equally optimal conditions for each.. I don't see any a priori or epistemic reason to think so and I am unaware of any relevant data sets .

Perhaps it's out there. I'll look for it. Such data would be critical to sustain a hypothesis of superior efficiency of space particularly since the volume of of nitrogen per volume unit of algae is similar. So, those touting scrubbers as more efficient than macro algae refugia should produce this data to show turf will produce more volume of algae in the same space than other macro alges will .
I think that's It's a fair and interesting question .

 

[Floyd R Turbo]

i have a small 2x1 foot water fall style.

12x24 is a HUGE scrubber. The current standard is 12 square inches of screen per cube of food per day. So unless you're feeding 20 cubes per day it's not going to grow right.