Skip to main content

Red Algae : Getting Rid Of Red Algae In The Aquarium

  • Author:
  • Updated date:

The Red Carpet


Red Algae Control

This is a guide on red algae control in marine aquariums. Popularly known as red slime algae, it is actually not an algae at all. It is a Cyanobacteria like spirulina is.

They are fully photosynthetic and are the devil to deal with once they start getting out of hand. Cyanobacteria, brown algae, hair algae and dinoflagellates are 4 of the biggest problem algae marine aquarists face.

Almost everyone has had to deal with them at some point or another. The reason why they're so widespread a problem is because they're so easy to get. And they're so easy to get because most of us aren't making sure our nutrients are at appropriate levels.

Bad Infestation

Red Algae And Nutrients

If you're looking to purchase red slime removers and are unsure if they really work then i'll go ahead and say that they work. But they don't address the cause of this infestation. Red slime will simply come back if used on its own. You can however, use them to accelerate the process. Chemi-Clean by Boyd Enterprises is by far the best slime remover on the market.

The appearance of pest algae in a saltwater aquarium can almost always be traced back to elevated nutrients. Nutrient control is how we're going to tackle red slime algae.

The two nutrients we are going to be concerned about are nitrates and phosphates. Both of them are constantly being produced in an aquarium.

Fish waste, fish food, detritus and anything that is rotting slowly in the tank contributes to nitrates and phosphates.

Lets start with fish waste. The more you feed, the more waste so we should begin by feeding smaller amounts at longer intervals. Uneaten food in the tank is less of a problem by feeding less as well.\

Next, we have to manually remove as much red algae as we possibly can. With red slime algae it isn't too difficult as they tend to form carpets that can be removed with ease. Scrape your live rock, glass, pumps and any other surface they are growing on. Make sure too remove any floating bits of red algae as well.

Clean up the entire tank by removing any detritus and uneaten you find.

Nitrate is removed primarily through water changes so perform as many as needed. Aim for a reading of zero. While phosphates are also removed during water changes, they tend to bounce right back within a day or two.

Employing phosphate removal media is highly recommended. Put it in an area of high flow. Follow the instructions and put the appropriate amount according to your aquarium size. Your phosphate levels should read zero in 48 hours.


Red Algae And Lights

If your bulbs are older than 6 months then you should change them. As bulbs age, the light emitted will slowly start changing in spectrum. In the case of reef lighting, they start entering the red spectrum.

And the red spectrum, is where all pest algae really thrive. Cut down your photoperiod to 4-5 hours a day.


Red Algae And Water Flow

Red slime algae really does not do well in high flow. If you notice where the majority of growth is taking place, it will probably be in a very low flow area.

You must increase flow to these areas immediately.

If you do all of the above then you are well on your way to getting rid of this pesky problem. But you must be patient, don't expect any real results after a few days. Getting rid of cyanobacteria takes weeks of diligent care. Follow these steps for a month and you'll likely be rid of red slime algae.

Read more :- Algae Control, Hair Algae, Pond Algae



PirateFX (author) on December 14, 2013:

Hi RJazz,

What kind of media are you using when you run a saltwater nano? Generally speaking, live rock and sand should be more than sufficient. From my own experiences (especially with new tanks), cyano (red algae) shows in the first few months and then slowly disappears, never to come back again.

So ditch the media, use live rock and sand and stock lightly in the beginning and see how it goes.

RJAZZ from Arizona on December 11, 2013:

I have a nano cube that developed red algae my first week with it due to a fish dying almost immediately. This was almost 8 years ago. The tank has been used off and on over the past ten years with downtime as much as 2 years. Its last use was as a freshwater tank. Whenever I try to go back to salt water, the red algae becomes a problem very quickly, and I am not sure how to address this. I have changed the media in the tank in the past, and I am thinking about getting new media, lights, and a new pump for the tank - I would like to start my saltwater cube up again, but fear the red algae. I also used the chemical cleaners. Is there something I can do BEFORE setting up the tank to get rid of anything in the plastics, etc???

Tess on November 06, 2010:

Can freshwater aquariums get red algae? I recently just read about brown algae, but I it seems that red and brown algae are completely different.

Peter (aquaman) on May 15, 2010:

Some aquarists in the battle against algae in the aquarium and to also to aerate and keep the water clear use a protein skimmer.

On my marine aquarium (1,000 gallon) I have a large protein skimmer. This is very efficient for removing unwanted nutriment that helps to feed algae.

However as my aquarium is literally algae free the protein skimmer only runs to my settings.

First I have plugged the protein skimmer timer into the lights timer (sort of piggy-backed). So when the lights go out the Protein skimmers timer has power cut to it. This means the skimmer does not run when the lights are switched off, during the hours of darkness.

However this means the skimmers timer looses its primary time of day setting. (It could be 9 AM real time and the timer might read 3 pm) "No worry"...During the daylight hours the timer is set to switch the protein skimmer on every two hours for a period of twenty minutes.

So no worry about the timer’s primary time. It just keeps on keeping on. After it’s rest over the hours of darkness when the lights switch back on it continues automatically to skim the aquarium at two hour intervals.

Remember also that the protein skimmer can also be a re-seeder of algae, so any algae cure running through it should also address the problem.


Peter (aquaman)

Peter (aquaman) on May 15, 2010:

To Pirate FX

Sorry in one paragraph my reply to your query on the use of ERYTHROMYCIN causing detrimental conditions in the aquarium.

I wrote: Also in my freshwater aquarium I have a 20-gallon tank.

I should have written:

Also in my freshwater aquarium SERVICE ROOM I have a 20-gallon tank.


Peter (aquaman)

Peter (Aquaman) on May 15, 2010:

In reply to your query (Pirate FX)

In the case of the treatment of an aquarium with ERYTHROMYCIN. It is important to realise I only treated a 200-gallon marine aquarium with a single tablet.

Also, Many aquarists worry about "Reversal" from loss of nitrifying bacteria. Years ago when trickle filters were introduced they placed a block of dense sponge rubber in the flow area in the sump. The thinking was. If you could create a dead pocket in the aquarium it would turn the Nitrate back to ammonia and nitrite.

This would help to lower Nitrate levels slightly meaning fewer water changes. After several months of operation of my trickle filters I could not see any marked difference either way.

As I live near the ocean it is quite easy for me each week to drive down to the bay (10 minutes drive) and collect 200 gallon of salt water for a partial water change (20%) This water I store for a couple of days in a black plastic tank.

The sun heats the tank being black plastic so after a full day the water becomes warm. I then pump it through a sediment filter and thence through an Ultra Violet steriliser. Note: My freshwater tropical water supply also comes through this same type of black plastic tank and UV system.

If I need a bit of aged freshwater in the marine aquarium I simply swing a supply tap over from salt to fresh. If I need a small amount of saltwater for any reason I can simply swing the tap to saltwater. When finished doing a saltwater change I can swing the tap to freshwater for a short time and this washes all the salt water from the pump.

Also in my freshwater aquarium I have a 20-gallon tank. This I fill also once each week. Each day a small pump switches on and runs for one minute only. This pumps water along a hose, which runs, under my home to the marine aquarium. This couple of gallon of saltwater runs into the aquarium at one end and at the other end the water overflows down the drain.

This keeps the level of the aquarium at a constant level aiding a small surface skimmer to keep the surface of the aquarium like polished glass. This aids greatly in oxygen exchange, another soldier in the fight against algae.

The single Tablet fixed the algae problem without any adverse conditions in the aquarium including the inhabitants.

The reason you have not heard much of the use of ERYTHROMYCIN TABLETS is that not many people have ever used it. Apart from the professionals.

I was lucky to have been told about it by (Marine Biologist) someone who had used it.

Any cure for aquarium problems carries a risk, but because you only use a single tablet to affect the red algae cure it should not adversely affect an aquarium.

Even the commercial cures can sometimes be devastating when unknowingly as I have found over the years that there may be a simple answer to many of our problems with aquariums.

It is to their credit that many aquarists world wide share their knowledge and experiences to help one another.


Peter (aquaman)

PirateFX (author) on May 15, 2010:

Hi Peter, thanks for the input :) The problem with antibiotics like Erythromycin is the fact that they can also wipe out beneficial that is needed by our marine aquariums. In theory anyway.

Having said that, i personally have no experience with Erythromycin and i'm very curious to know how your aquarium did after its use. Did you notice any ammonia or nitrite spikes after use? Perhaps if we get the dosage right it could take care of the cyanobacteria while minimizing damage to the beneficial bacteria, thereby making it a very viable option. Thanks again Peter.


Peter (aquaman) on May 15, 2010:

Many years ago I had an ongoing problem with Red Algae in a 200-gallon Marine Aquarium. No matter what I did it was near impossible to eradicate. The pipe work and filters were also a problem as the spores of the algae were resident in these areas.

I was to the point of shutting down the marine aquarium. Then one day I was out in my boat doing environmental monitoring of the ocean sea grass beds with a group of marine biologists.

I mentioned about the problem I had been having with the red algae, and told him it had not been possible to eradicate. Anyway he told me to try using a single ERYTHROMYCIN TABLET “NOT CAPSULES”. Then do a 60% water change after 1 week. Also do not feed the fish for a period of one week starting from the time you use the ERYTHROMYCIN TABLET.

On arriving back home I got a packet of tablets from the Vets. I added it to the aquarium in the evening. The aquarium rocks, coral and glass had quite a bit of the algae covering it looking like red velvet.

The next morning as I walked across the lounge room I looked towards the aquarium. I could not believe my eyes. All traces of the red algae had disappeared. The aquarium was spotlessly clean.It looked like someone had actually srubbed the coral, rocks and glass clean. The water was also crystal clear.

The red algae problem never returned to that early aquarium. So I never got the chance to use the rest of the ERYTHROMYCIN TABLETS.

I know that some aquarium cures do contain ERYTHROMYCIN, If there is one in your local pet shop stating that it will address the problem of red or other algae’s in the aquarium, it may also work for you.


Peter (aquaman)

Related Articles