Mega-powerful Nitrate And Phosphate Remover Replaces Skimmer, Refugium

[SantaMonica]

Update Of The Day:

Waste is Food: Reef tank owners sometime get into the frame of mind of "food is food, and waste is waste". Thus they put food into the tank, and they remove waste from the tank (skimming, siphoning, waterchanges.) But actually, both food and waste are Organic, and thus are both "food" (food for something, somewhere). Corals and inverts may not directly eat the big krill that you feed your fish, but they do eat the waste from those fish. Further info:
http/www.reefkeeping.com/issues/2002-07/eb/index.php

 

[SantaMonica]

Successes of the Day:

todj2002 on the SWF site: "since installing scrubber, N and P are still both at zero. i cleaned it again today. not any big deal, but huge progress for me. finally beat the algae after two years of trying. using scrubber with chaeto and RO water now. finally getting somewhere."

Marine_Nick on the RP site: "Thought I'd update on my screen. When setting it up I was concerned about light pollution from the sump into the room, and noise from the falling water. as my tank is on an outside wall, I wanted to put the screen outside if possible. I already had an old 18 x 12 x 12 tank, so had it drilled and put a small wier in it, the water is pumped from the sump up and out through the wall to the screen, runs down the screen, through the weir, back through the wall and back into the sump. All of this is in a small shed I made which contains all the lighting etc, my screen is 18 inches tall by 12 inches wide and has a light on either side. Screen has been running now for 4 weeks, and my nitrates have dropped from 30 to 7 and phosphate from 0.25 to 0. In the last 4 weeks, nothing else has changed in my tank other than more fish being introduced, and therefore more food being added, and still the parameters have dropped!! Overall I'm really happy with results so far and hope to see the nitrates drop to zero in the next week or two. Big thanks to Santa Monica for this thread and all the info!"

jtrembley on the MD site: "I got frustrated with the skimmer (EuroReef, rated for 80) on my 40 gallon a while back. It was pulling out *lots* of crud, but I was having trouble with detritus building up, and rising P values. Since yanking the skimmer and DIYing (poorly) a rev. 2 scrubber [acrylic box style], phosphates and nuisance algae are down, and the backlog of detritus is slowly being consumed. I'm seeing lots more worms (particularly the small ones that build white, spiraling tubes) and 'pods (amphi- and cope- that is, but not octo-). Here's the funny thing: at the 3 year stage of my 40, I started getting lots of nuisance algae, despite having one of the hands-down best skimmers for small tanks, an MCE600, on it. Thinking that I was doing something wrong, I put an MC-80 on it. After another year, I started getting more and more detritus building up in the display, despite having a *lot* (over 2k GPH) of flow. And then I noticed something else: I no longer had many fan and bristle worms, amphipods, or copepods left in the sytem, either. So...I started swapping out my old LR for new, to replenish the critters. And I tried Fauna Marin and vodka dosing. But the critters weren't really spreading, and the nuisance algae was getting worse, and my P was rising despite water changes. So, I thought about it, poked around, and looked at Eric Borneman's study of *fresh* skimmate (i.e., not stuff that was left in the cup to rot). And I realized something: having a high quality skimmer on the tank was probably stripping the tank of big chunks of its potential cleanup crew. So I took off the skimmer, and put in a turf screen to cover the water's surface in what used to be the skimmer's chamber in my sump. Low and behold: I'm feeding more; I'm once again seeing fresh worm tracks in my sand bed; the copepods are back; the nuisance algae is dying off; P is undetectable by hobby kits; and the detritus is slowly clearing up. And I'm not doing as many water changes. I checked pH this morning, it was 8.2, before the lights are on. I'm honestly not seeing the down side. So yeah, removing the skimmer and putting in a $5 turf scrubber fixed my tank of "old tank syndrome". Just for giggles, I just tested my N (0.2 or 0.5 Salifert) and P (0.05 Hanna photometer). No visible HA, turfs, or cyano in the display, and I can (easily) feed 2X cubes of Hikari mysis, some dulse, and 2 scoops' worth of Reef Chili daily (again, in a 40). And I haven't done a water change in a month. I'm honestly not seeing a downside to scrubbers at this point."


Successes of the Day:

todj2002 on the SWF site: "since installing scrubber, N and P are still both at zero. i cleaned it again today. not any big deal, but huge progress for me. finally beat the algae after two years of trying. using scrubber with chaeto and RO water now. finally getting somewhere."

Marine_Nick on the RP site: "Thought I'd update on my screen. When setting it up I was concerned about light pollution from the sump into the room, and noise from the falling water. as my tank is on an outside wall, I wanted to put the screen outside if possible. I already had an old 18 x 12 x 12 tank, so had it drilled and put a small wier in it, the water is pumped from the sump up and out through the wall to the screen, runs down the screen, through the weir, back through the wall and back into the sump. All of this is in a small shed I made which contains all the lighting etc, my screen is 18 inches tall by 12 inches wide and has a light on either side. Screen has been running now for 4 weeks, and my nitrates have dropped from 30 to 7 and phosphate from 0.25 to 0. In the last 4 weeks, nothing else has changed in my tank other than more fish being introduced, and therefore more food being added, and still the parameters have dropped!! Overall I'm really happy with results so far and hope to see the nitrates drop to zero in the next week or two. Big thanks to Santa Monica for this thread and all the info!"

jtrembley on the MD site: "I got frustrated with the skimmer (EuroReef, rated for 80) on my 40 gallon a while back. It was pulling out *lots* of crud, but I was having trouble with detritus building up, and rising P values. Since yanking the skimmer and DIYing (poorly) a rev. 2 scrubber [acrylic box style], phosphates and nuisance algae are down, and the backlog of detritus is slowly being consumed. I'm seeing lots more worms (particularly the small ones that build white, spiraling tubes) and 'pods (amphi- and cope- that is, but not octo-). Here's the funny thing: at the 3 year stage of my 40, I started getting lots of nuisance algae, despite having one of the hands-down best skimmers for small tanks, an MCE600, on it. Thinking that I was doing something wrong, I put an MC-80 on it. After another year, I started getting more and more detritus building up in the display, despite having a *lot* (over 2k GPH) of flow. And then I noticed something else: I no longer had many fan and bristle worms, amphipods, or copepods left in the sytem, either. So...I started swapping out my old LR for new, to replenish the critters. And I tried Fauna Marin and vodka dosing. But the critters weren't really spreading, and the nuisance algae was getting worse, and my P was rising despite water changes. So, I thought about it, poked around, and looked at Eric Borneman's study of *fresh* skimmate (i.e., not stuff that was left in the cup to rot). And I realized something: having a high quality skimmer on the tank was probably stripping the tank of big chunks of its potential cleanup crew. So I took off the skimmer, and put in a turf screen to cover the water's surface in what used to be the skimmer's chamber in my sump. Low and behold: I'm feeding more; I'm once again seeing fresh worm tracks in my sand bed; the copepods are back; the nuisance algae is dying off; P is undetectable by hobby kits; and the detritus is slowly clearing up. And I'm not doing as many water changes. I checked pH this morning, it was 8.2, before the lights are on. I'm honestly not seeing the down side. So yeah, removing the skimmer and putting in a $5 turf scrubber fixed my tank of "old tank syndrome". Just for giggles, I just tested my N (0.2 or 0.5 Salifert) and P (0.05 Hanna photometer). No visible HA, turfs, or cyano in the display, and I can (easily) feed 2X cubes of Hikari mysis, some dulse, and 2 scoops' worth of Reef Chili daily (again, in a 40). And I haven't done a water change in a month. I'm honestly not seeing a downside to scrubbers at this point."

 

[SantaMonica]

.
Update: The Trick of Dark Brown Algae

This has now happened to many people who have new scrubbers. They get early growth, but it's not the green stuff that they see in most pics. Instead it's a dark brown super-thick "coating", or a black "tar", that looks like it was poured on:

What you have here is the type of algae that grows when nutrients are extremely high (!). After a few cleanings, when the nutirents come down, the color will lighten up to some balance point where it will stay. The big problem, however, is that people think the screen is not growing, so they leave it in to "grow more" (by not cleaning it). BIG MISTAKE! This type of algae does not grow thick, at all. It never gets more than 1/4" (6mm) or so. And worse, since it's SO DARK, it block all light from reaching the bottom layers, thus causing those layers to die and release nitrate and phosphate back into the water. So the solution is to clean ANY and ALL dark brown/black algae right away, and don't even wait until the end of the week. Basically, if you cannot see your screen, then light is not reaching it and it needs to be cleaned. You'll only have to do this a few times before the nutrients come down and the algae color lightens up. Don't fall for the Dark Brown Algae Trick.

 

[SantaMonica]

Success of the Day:

"Mxett" on the MD site: "I installed a simple [scrubber] over my refugium. It uses an old plastic fruit juice container and a syphon [which makes a surge device] to dump 2 litres onto a white plastic chopping board which lays horizontally over the top of the refugium. A reflective CFL [bulb] is situated just 10cm above this board. The surge occurs every 30 seconds, lasting for 15 seconds. Growth on the [scrubber] has been excellent. Harvesting the algae is performed every 1 to 2 weeks per SM's instructions. [should be weekly ] N & P have never been detectable in my system, BUT I have always struggled with a very persistant nuisance red algae! It threatened to overtake my entire tank in the months before installing this [scrubber], which is only a modest size for my 800 litre cube. Anyway, after 3 months of using the [scrubber] I can confidently say I have little to none of this red algae left! My purple tange eats it and always has, but with less nutrients available to it, it has just withered away, and he just finishes it off. Overall a great success over a difficult pest. Thanks SM for providing the inspiration and idea to create, install and use such a cheap, easy and effective natural filter."

 

[SantaMonica]

Scrubber FAQ 2.0 is now up:
http/www.algaescrubber.net/forums/viewto...hp?f=9&t=68

 

[SantaMonica]

.
Today's Success of the Day, from OceanParks on the MFT site, had a good story to it. So here it is with his posts and the dates:

12/17: SantiMonica: I've also built and installed your screen. I am on day 5. I have the brown/green film and was wondering how long before you start to see a noticable drop in Nitrates? I have a 110 gal reef tank with fish and my Nitrates are at 20ppm. Thanks.

12/18: and what wattage bulb would you suggest (pc flood) would you recommend for better results?

1/5: Ok. So I read your thread and built a scrubber (a true hobbyist). I'm in the middle of week three and I've done 2 cleanings and one freshwater rinse. Nitrates began at 30ppm and are now down to 5ppm (with the help of a 40% water change) in this 110 gallon reef tank. I removed the skimmer and UV sterilizer to allow room for the scrubber. I will compose a more formal, descriptive posting in the near future on my setup - one that I hope you will use in your RESULTS postings. I am still trying to get a grip of this thread thing....it is my first one. Did you say that you were getting better results with a different light bulb. If so can you please specify? Thanks! Enjoy the pictures! What do ya think?

1/5: [Remove the filter socks.] Really about the socks? I'm afraid of too may particles floating around. I'll give it a try. Also, can I get the plant-grow bulb at Home Depot and is it in Flood form? I have the timer set for 16hrs on and 8hrs off, however, I get excited and want to turn them on early for (in my mind) faster results. Probably no better results? Ok. Off with the socks. Good idea. Is the grow-light a flood light like those pc flood light? Thanks for the help! I will send a full report and pictures in a few weeks!

1/7: I replaced my flood lights with 2700K "soft white" PC Flood lights today. Same wattage...they just seem dimmer. It's that red light. Hope it works better.

1/12: I spent some time reviewing the begining of this thread and noticed that most of the pictures showed bright green thick mats of algea on the screen. I am not getting that after 5 weeks. I am getting dark brown/red stuff and it's only about 1/4" combined. [The stealthy high-nutrient black/brown algae that must be removed right away.] I did use some of the brown/red stuff to seed the new screen when I built it. Should I rebuild the screen and seed it with some hair algae from the tank? [not now.] Also, at the bottom of my sump, beneath the screen there is red/brown slime forming (see picture). Should I remove/treat for this or can it be concidered benefitial? [leave it.]

1/12: Here is 5.1 oz of the black oil (I read from your other site). Funny enough, under the layer of black stuff there was some bright green algae. Any thoughts on that? [that's why it needs to be removed right away.]

1/20: CLEAR!!!!!! My scrubber has been up since December 18th and tonight the Nitrate test (Nutrafin) read clear indicating 0 nitrates! Awesome. Thank you SantiMonica. Awesome. 0 Nitrates on the Salifert Test too.
.

 

[SantaMonica]

One of the big benefits of a scrubber is that it keeps food in the water. Here is an update pertaining to this:

Part 1 of 7:

Taken from "Reef Food" by Eric Borneman:
http/www.reefkeeping.com/issues/2002-07/eb/index.php

"Detritus, marine snow, particulate organic material, and suspended particulate matter are all names for the bits of "dirt" [food] that flow around the reef; material that is composed of fecal material, borings, algae, plant material, mucus, associated bacteria, cyanobacteria and other particles. Decomposers (mainly bacteria and associated flora and fauna) break down waste material in the water, on the reef, and primarily, in the soft sediments. The result of their presence and action is not only a food source in and of itself, but provides raw material for channeling back into the food chain, largely through the benthic algae and phytoplankton.

"Phytoplankton [food] are small unicellular algae, or protists, that drift in the water column. They may be very abundant in and around coral reefs, and they are capable of absorbing large amounts of organic and inorganic nutrients. [...] Some of the reef animals can feed directly on phytoplankton; many soft corals, some sponges, almost all clams, feather-duster worms, and other filter feeders utilize phytoplankton directly as a food source. Small animals in the water column, termed zooplankton [food], also utilize phytoplankton as a food source. For the smaller zooplankton, phytoplankton and bacteria are the primary food source.

"Both of the [photos not shown] are from reefs on the Great Barrier Reef, Australia. The left photo shows the clear "nutrient poor" (oligotrophic) waters of the outer reefs. The right photo is of an inshore "nutrient rich" lagoon reef off Townsville. Notice how coral coverage in both systems is high, and even though the green phytoplankton-filled lagoonal reef is nutrient rich, it supports a high density of Acropora.

"Coral reef food sources, then, are largely produced by the ocean. Bacteria, detritus, phytoplankton, zooplankton, small benthic fauna, mucus, and dissolved organic and inorganic material of various types and sizes are what comprise the majority of food on a coral reef.

"In aquaria, we are faced with several realities. Our phytoplankton and zooplankton populations are generally negligible to non-existent in comparison with coral reef communities. Those which do exist are either rapidly consumed without having a chance to reproduce, or they are rapidly removed or killed by pumps and filtering devices or suspension-feeders. Coral mucus, bacteria, detritus, larval benthos and other "psuedo-plankton" might be present in a reasonable amount if the water column were not stripped. On the other hand, dissolved organic and inorganic material [nitrate, phosphate] levels are frequently much higher than they are in the ocean. [...] Even very well maintained aquaria are generally found with much higher levels of nitrogen and phosphorous than wild communities. Even though many desirable organisms are able to utilize these nutrients, levels in most aquaria are very unnatural, and coral reefs under such conditions often wane or die - a process known as eutrophication.

"It is the lack of water column-based food that results in limited success with the maintenance of some desirable animals, such as crinoids, flame scallops, clams, certain corals, sponges, bryozoans, and many other invertebrates. Even the symbiotic (zooxanthellate) corals [like SPS] suffer, despite many obvious long-term successes with these animals.

"In terms of previously mentioned export mechanisms, it really does little good to be cultivating or adding more food material in the water column if it is all being rapidly removed by filtration devices. Live rock and sand provide abundant filtration, and some of the articles in past issues describing the set-up and use of unskimmed tanks are, in my experience, something that should be seriously considered. Algae Turf Scrubbers are also viable systems that provide low ambient water nutrient levels [of nitrate and phosphate] while maintaining higher amounts of food and particulate matter in the water. I also feel that if protein skimmers are used, they should probably be used in an intermittent fashion.

 

[SantaMonica]

Thought Of The Day:

A few folks have seen (or thought that they had seen) their skimmers "working less" or "producing less" after their scrubber started working. While this may have happened for other reasons, there is really no direct reason that a scrubber should cause a skimmer to produce less. This is because a skimmer and a scrubber remove different things: Scrubbers remove Inorganic Nitrate and Inorganic Phosphate, which are invisible, and which are the things that your test kits test for. Skimmers remove food (Organics). So having a scrubber remove the Inorganic Nitrate and Inorganic Phosphate really shouldn't cause a skimmer to remove any less food (unless you are feeding less). What MIGHT be happening, is that less Inorganic Nitrate and Inorganic Phosphate in the water means there is less food for bacteria (bacteria eat Organics AND Inorganics), and if there is less bacteria, then there is less to skim out.

 

[SantaMonica]

Update of the Day: New Research on Skimmers and Organics:

The whole point of scrubbers is that they remove Inorganic Nitrate and Inorganic Phosphate, which are the things your test kits measure, and which are also the things that cause nuisance algae to grow. The other good point about scrubbers is that they leave Organics (food) in the water for the corals and fish and bacteria to eat (the bacteria also then become coral food.) People who prefer skimmers, however, say that skimmers removes Organics (food) before they break down into Inorganic Nitrate and Inorganic Phosphate.

I say, why not just feed less, instead of feeding more and then removing it with a skimmer? Let's look at it from their viewpoint. Their viewpoint is "Feed more, and remove the excess Organics (food) with the skimmer." Well, the current January 2009 issue of Advanced Aquarist just published extensive research into how well different skimmers remove Organics. They refer to Organics as "TOC", which is the Total Organic Carbon; TOC is the the combination of Dissolved Organic Carbon (DOC), and Particulate Organic Carbon (POC). Here is the article, and this is what it said:

http/www.advancedaquarist.com/2009/1/aafeature2

"In addition to some dissolved organics, small particulates and microbes (bacterioplankton, phytoplankton) can be removed at the air/water interface of the [skimmer] bubble as well (Suzuki, 2008). The skimming process does not remove atoms/molecules that are strictly polar and readily dissolve in water, such as some organics, salts, inorganic phosphate, carbonate, etc.

"The skimmer pulls out all of the TOC that it is going to remove by the 50-minute mark. Beyond that time point, nothing much is happening, and the TOC level doesn't change much.

"Thus, all skimmers tested remove around 20 - 30% of the TOC in the aquarium water, and that's it; 70 - 80% of the measurable TOC is left behind unperturbed by the skimming process. It may be possible to develop a rationalization for this unexpected behavior by referring back to Fig. 1. Perhaps only 20 - 30% of the organic species in the aquarium water meet the hydrophobic requirements for bubble capture, whereas the remaining 70-80%, for whatever reason, don't."

So, the strength of skimmers (since they don't remove Inorganics) is supposed to be that they remove Organics before they break down. But this research shows (once again) that they don't even remove the Organics. Here is additional 2008 reasearch that shows the same:

http/www.advancedaquarist.com/2008/8/aafeature3
http/www.advancedaquarist.com/2008/9/aafeature2

 

[SantaMonica]

Results of the Week:

jtremblay on the MD site: "the last few strands of HA have disappeared from my 40's display, and the build-up of detritus is continuing to go down, despite there being no skimmer on this tank."

nitschke65 on the SWF site: "My biocube is currently being filtered by my custom [nano] turf scrubber in chamber two; there is also a ball of chaeto in the bottom af chamber two, and a bag of Chemi-pure Elite in chamber three. My protein skimmer stopped working two or three weeks ago. (My mushrooms and zoas have never looked better!) I also have some polyps, hammers, and galaxia. There's a few nassarius, and a few hermits, an emerald crab, and possibly a pepermint shrimp. There's a lawnmower blennie, two green chromis, a scarlet hawk, and a Potter's angel. I haven't cleaned my screen or done a water change in 2 weeks [bad!]. This mornings readings: Ammonia - 0 Nitrites - 0 Nitrates - 0

Skunkbudfour20 on RC: "Yes i built one, Yes i am running it, and YES my nitrates, nitrites, ammonia and phosphates all dropped to almost 0 within the first 3 weeks, and yes algae growth in my display has come to a stop, and slowly recedes... I am still running my skimmer, even though it doesnt seem to be doing AS much, its still doing something for now."

Worley on the AS site: "As for lights, I have seen an improvement in the type of algae growing and in the overall amount of growth since changing bulbs to the lower 3500K colour temp. I've been getting more hair [on the screen], macro algaes, some interesting dark green very very long hair-like algae (6"+ long). The cyanobacteria [in the display] is nearly completely gone, along with less brown slime algae, both in the tank and on the screen. And best of all, still no water changes, nearly 5 months on, with good calcium, dKH and PH. I've easily saved the price of the equipment used to make the scrubber from not having used an entire bucket of salt, and everything in the tank looks more healthy than I've ever seen in a marine tank I've kept before, I'm loving it, and so is my girlfriend!"

 

[SantaMonica]

Update of the Day: Freshwater Cleanings

You absolutely must use freshwater, in your sink, when cleaning your screen once a week. If your weekly cleaning gets delayed, at the very least turn the pump off and pour RODI over the screen to kill the pods. Otherwise the pods start growing underneath, eating the algae, then falling off into your water. You will not see the holes they make unless the algae is very thin. It becomes an issue of the scrubber not removing as much nitrate and phosphate, because the pods eat the algae you've grown, and then re-introduce the nutrients back into the water. FW of course, kills the pods. SW does not. So use FW weekly. And don't worry about getting rid of all the pods; you won't. The next day there will be millions more.

 

[SantaMonica]

Part 3 of 7:

Taken from "The Food of Reefs, Part 3: Phytoplankton" by Eric Borneman
http/www.reefkeeping.com/issues/2002-10/eb/index.php

"Phytoplankton are the major source of primary [food] production in the ocean, and one of the most important driving forces of global ecology. In fact, phytoplankton production influences all life, by being at the lowest rings of the food chain.

"The reason [phytoplankton] are so important on a regional or global scale is simply by virtue of the fact that the upper 200 [meters] of oceanic waters is filled with phytoplankton and covers over 70% of the earth's surface.

"What eats phytoplankton? In the water column, zooplankton [food] are without question the primary consumers of phytoplankton. Zooplankton grazers vary according the area and the time of year, but include primarily ciliates, copepods, amphipods, and tintinnids.

"Stony corals are generally not well adapted to the sieve or filter type feeding that characterizes the soft corals (Fabricius et al. 1995, 1998). They are, however, well suited to the capture of zooplankton prey.

"It is of paramount importance to recognize that the biomass of potential grazers [which need food] in an aquarium is many times what it would be in the same volume of water or surface area as the bottom of oceans or on reefs, and also, that the availability of water column borne food is many times greater in the ocean than in an aquarium.

"Perhaps most importantly, is the almost ubiquitous interaction between bacteria and phytoplankton. Phytoplankton release dissolved organic substances, and bacteria utilize them as nutrient sources. Most phytoplankton cells, especially large ones, are coupled nearly continuously with coatings of bacteria [which are consuming the dissolved organic substances].

"The amounts of phytoplankton present in reef aquariums are not known but are probably considerable. However, they are also probably rapidly removed by grazing and export devices [skimmers].

 

[SantaMonica]

Bob the (reef) Builder on the SARK site made this PDF for a club presentation three months ago, and I just found it; maybe it could be used by others:
http/www.radio-media.com/fish/AlgaeFilters.pdf

 

[SantaMonica]

Scrubber FAQ 3.0 is now up, with about 50 percent new info:
http/www.algaescrubber.net/forums/viewto...&p=386#p386

 

[SantaMonica]

Results of the week:

Broder on the SARK site: "I have been running my tank with an algal filter for about 3 months now. I removed the skimmer on the 10th last month. My display has never looked better. The [nuisance] algae has almost totally dissapeared. My SPS colonies are thriving. Not only are they growing well, but the colouration has become vibrant due to 0 PO4 (Salifert test) and 0 nitrate. I've seen better colouration in systems that were using Zeovit, but I'm more than happy with the results the algal filter achieves."

Sly on the SWF site: "The back glass used to be absolutely covered in green algae, but now it's staying clean on its own. I have never cleaned it. The rocks weren't that bad, but there were some patches of cyano in places that are now gone. It now seems to be staying cleaner on its own. My ORP has started rising again and is a 270mv without ozone. I don't know if it's related but as my tank levels have improved lately, my Mandarin is coming out more in the day time. This is the first picture I have ever been able to get of him in the open... and I've had him for over 2 years. The live rock and the substrate both have zero algae on them"

TODJ2002 on the SWF site: "i added a scrubber several months ago after reading this thread. my nitrates and P slowly lowered and went to zero for the first time. they have both been at zero since. everytime i check levels i am expecting to see a rise, but always zero. i also added cheato to my system and i believe boths items are a must for any system."

Adee on the SARK site: "Ok so its been about 6 weeks since i fired this scrubber up. Did the 1st "harvest" on just the one side; i'll do the other side next weekend. My phosphate reading is a zero according the Elos color chart... and for the very first time the complete back glass pane has broken out with coraline algae. Its never done that before due to the back always being covered with the normal glass algae/diatoms. Since the latter no longer appears, the coraline is now growing. I'm sure in a few weeks I'll have a complete pink wallpaper at the back. The fact that the scrubber makes the ideal platform for all this gunk to grow OUTSIDE my display tank, was well worth the investment."

Bob the (reef) Builder on the SARK site: "Both my filters are going great guns. Probably the best is the sun [powered] one, it's big and now that its settled, grows algea like crazy. My phospates down to 0.00 - 0.01ppm on a Hanna meter. Never seen it this low before. My corals are starting to grow and colour up really well now."

RentalDeceptionist on the UR site: "Ooh the [nuisance] algae. Well, it has certainly receeded massively. It's not 100% gone but I feel I'm on top of it. The hair algae which virtually smothered every flat surface is now down to about 20% of its mass, and there is more rock than algae. I do believe decreasing the lighting has helped."