Mega Powerful Nitrate and Phosphate Remover - DIY!


Superstar Fish
Here is this weeks pics before cleaning. This waterfall scrubber is lit by LED's and has 4 660nm on one side and 4 660nm and 1 450nm for a total of 5 on the other. Its pretty obvious what side has the blue 450nm. The growth speaks for itself. I have went many months waiting to see if it was just a fluke that one side did better then the other but it was like this every time. I even put the 5 count side further from the light and diffused it with two diffusers to make the light intensity more equal to the 4 count side. Still, the side with one blue blows away the all red side.

Here is a pic from the side showing the 3D thickness.

Here is the blue/red side.

Here is the all red side.

A close up of the red blue side.

The algae grows right out toward the red/blue side, its crazy how is does this. This is almost 3 weeks worth and my screen is one cube over sized for what I feed.

Feb 28, 2013
Phosphate flow out of rocks

Many people, when they get their scrubber running for the first time, get worried when more (not less) algae starts to grow on their rocks. It seems really strange, especially when nitrate and phosphate have gone lower than before. What is happening is that phosphate is coming out of the rocks. Remember, phosphate is invisible, so you can only see the effects of it, and it always "flows" from higher concentrations to lower concentrations (just like heat does).

Example: If your room is warm, and you put a cold object on the floor, heat from the air in the room will "flow" into the object until the object and the air are the same temperature. Example 2: If you put a hot object on the floor, heat will "flow" out of the object and go into the air in the room, again, until the air and the object are the same temperature. Now suppose you open your windows (in the winter). The warm air in your room will go out the windows, and it will get colder in the room. The object on the floor is now warmer than the air, so heat will flow out of the object and into the air, and then out the window.

Think of phosphate as the heat, and your rocks as the object, and your windows as the scrubber. As the scrubber pulls phosphate out of the water, the phosphate level in the water drops. Now, since the phosphate level in the water is lower than the phosphate level in the rocks, phosphate flows from the rocks into the water, and then from the water into the scrubber. This continues until the phosphate levels in the rocks and water are level again. And remember, you can't see this invisible flow.

This flow causes an interesting thing to happen. As the phosphate comes out of the rocks, it then becomes available to feed algae as soon as the phosphate reaches the surface of the rocks where there is light. So, since the surface of the rocks is rough and has light, it starts growing MORE algae there (not less) as the phosphate comes out of the rocks. This is a pretty amazing thing to see for the first time, because if you did not know what was happening you would probably think that the algae in the scrubber was leaking out and attaching to your rocks. Here are the signs of phosphate coming out of the rocks:

1. The rocks are older, and have slowly developed algae problems in the past year.

2. The scrubber is new, maybe only a few months old, and has recently started to grow well.

3. Nitrate and phosphate measurements in the water are low, usually the lowest they have been in a long time.

4. Green hair algae (not brown) on the rocks has increased in certain spots, usually on corners and protrusions at the top.

5. The glass has not needed cleaning as much.

Since skimmers, filter socks, etc don't remove any nitrate and phosphate, and waterchanges and macro's in a fuge don't remove much, most people have never seen the effects of large amounts of phosphate coming out of the rocks quickly. But sure enough, it does. How long does it continue? For 2 months to a year, depending on how much phosphate is in the rocks, how strong your scrubber is, and how many other phosphate-removing filters you have (GFO, carbon dosing, etc). But one day you will see patches of white rock that were covered in green hair the day before; this is a sure sign that the algae are losing their phosphate supply from the rocks and can no longer hold on. Now it's just a matter of days before the rocks are clear.

Coming this summer 2016:
Waterfall algae scrubber
Version 2

After I invented the waterfall scrubber in 2008, it's great that so many people got to DIY it, and it's also great that lots of builders/sellers used it as their design up until the current day. It's had over 7 years to gather hobbyists.

2012 was a good year though, when I introduced the upflow scrubber. It's only had 3 years to gather hobbyists, but offers them what they did not have before: a compact place where they can put a scrubber that does not spill over when it fills up.

Now that the upflows are established, it's time to do some more work on the waterfalls. They've been unchanged since 2008, and almost every part of them can be improved. So over the next year or two I'll post up the improvements piece by piece. Hopefully the improvements will be useful to all.

"Algae scrubbers are one of the few, if not the only, nutrient removal systems that give me something back: Growth. It's a no brainer" -- Jim Stime, LA Fishguys

"I see algae scrubbers as the single most significant nutrient exporter you can have" -- Stephen Babcock, The Corner Reef, Columbia, Illinois, USA

"I am very happy with my [upflow scrubber] which is working great. I will be [using] more scrubbers for my other 8 tanks" -- Bruce Ashcraft

"The [floating upflow scrubber] is really useful and highly necessary for my tank. So I really can't be without it for too long" -- Jason Pappin

"My [tiny upflow scrubber] works great, and I was thinking about another one. The biggest difference I seen was my phosphate level went from 0.11 to 0.03-0.06 range " -- venom on the CR site:

"The [upflow scrubber] is producing lots of lovely green algae for me" -- K19RKS on the UR site.

"Growth from our [upflow scrubber]" -- Alyse Fisher:

"Tank is heavily fed and [upflow scrubber] definitely seems to have made an improvement since the algae started growing" -- Jason Oneppo

"[floating scrubber is] growing very well. Love the in sump design. Will probably do another down the road as I increase my bioload." -- Erik Sulman

"I'm getting good results from my [2 upflow scrubbers].. It's bringing my phosphate down and starting to get some decent hair algae my tangs love" -- Dane Wilcox

"WOW! 173grams. Two weeks growth [on the floating scrubber]. We LOVE it! The growth rate of the chaeto in our refugium had been steadily decreasing over the past six weeks or so. Yesterday, it became obvious that the chaeto had started to melt/die-off and needed to be removed from the system" -- Mike&Terry on the R2R site:

"There is getting to be some nice looking green hair algae in it" -- Dane Wilcox

"I clean my [scrubber] once a week. Definitely helped lower my nitrates." -- Nagrom on the MR site

"I installed a [upflow] ATS in my 3rd chamber with the return pump in my 29 biocube works well for me. My nitrates stay between 5 ppm or lower. Phosphates are usually .04 or lower -- Saltyphish on the R2R site"

"I didn't really expect much from the [upflow scrubber] and put it in my sump. After about 3 weeks the algae was in abundance and now I have to clean it every 2 weeks" -- Jukeboxjury on the RF site.

"The [upflow scrubber] is doing really great. The first time it was full of green small rounded shape of algae, feels like jelly, i dont know what that is. The second and third week after that is full of green hair algae. Water parameters are great, with readings from hanna checker and salifert testers" -- Yuppy Suhandinata:

"The scrubber is working great! getting a lot of nice growth" -- Mike Buechs

"I installed a [small upflow scrubber] in my 3rd chamber with the return pump in my 29 biocube, works well for me. My nitrates stay between 5 ppm or lower. Phosphates are usually .04 or lower" -- Saltyphish on the R2R site.

Other growth pics:

Damien Kwok:

Quy Van:

Marlon McNeish:

Alanreef on the R2R site:

- C. Smith


New Fish
Nov 20, 2016
I built an upflow scrubber, and it worked fabulously, but I'm a terrible housekeeper and I hate putting my hands in the tank, so I would often go loooong periods of time without getting cleaned. I decided that the inner layers of algae were dying without light and probably making my aquarium less healthy than if the (neglected) scrubber weren't there in the first place, so I took it out. But now I have this exact same HOB filter that I'd like to turn into a scrubber. No more putting my hands in to clean the algae screens! I'm curious about the components shown here, I imagine one is a reflector, and perhaps the big bulky one is LED lights? This post is a few years old, maybe I can find more compact lights now? Does anyone know where to buy/what to search for for the LED lights?
This is a Millennium 3000 HOB filter that I threw together.


To scrubber users who like science: Marine Biology Basics... the videos:

- Ocean Productivity
- Photosynthesis part 1
- Food Chains vs. Food Webs
- Nutrients and Primary Production
- Chlorophyll - Zooplankton and Primary Production - Bacteria - Food Webs - Microbial Food Web - Trophic Pyramids