Cyano, Cyano-bacteria, red slime algae
They are all names for an algae that is very common in reef aquaria, plagues and frustrates many people and their tanks, and is also, surprisingly, extremely easy to eradicate compared to other nuisance algae in marine Aquariums.
First of all you need to find the cause of it, and it can be a problem in even the lowest nutrient tanks. Mostly it is a product of a few things, the main ones being
- high levels of nitrogen (and not only nitrate, cyano can lock, harvest and utilise ionic nitrogen in the form of ammonia and nitrite as well as many organic bound forms of nitrogen)
- any levels of phosphate, even if none are detectable in the water column
- low water flow, and most importantly the export and movement of detritus and organics from the system ( or in this case, lack of) into the filtration where they can be collected and removed
I have recently been consulting on a friends tank (2000 litre marine wonderland) and the tank consistently reads 0 nitrates and 0 phosphates, on multiple testings with high accuracy testing kits. However, and it has been an issue for quite some time, that the tank requires more flow.
This however is beside the point as he has not had a cyano bloom for quite some time until now, and it is only occurring in one of the tanks (this system consists of two identical tanks plumbed into the same filtration system) the cause we believe is that one of the wavemakers at the back of the tank is blowing the substrate off the eggcrate the live rock is sitting on. This is enough to create enough circulation under the substrate, blowing water with organics and potential phosphates up through the sand bed.
Now, as i have mentioned this system runs very close to 0 nutrients, in fact it is too clean, and it has meant the system needs to be fed a lot more for the benefit of the corals, which is mainly SPS. This however does not mean that there is not phosphate in the system, in fact, it is impossible that there is no phosphate being produced in the system, the zero readings we are achieving are the readings in the water column, and are simply either being taken up by photosynthesis or by the nutrient export system in place in the tank, and this is the reason that we are not getting a reading.
However, water with trace levels of phosphate is still being pumped down in, and through the substrate in this case, and as we know and has been explained in previous posts, phosphate will bind to calcium carbonate based substances, like substrate in a marine tank. Substrate also has a lot of organics and sediments in it as well which, with increased water flow through the substrate bed may have also contributed to the accelerated breakdown of these sediments into nitrate and phosphate (instead of the normal biological processes in the sand bed, however shallow or deep, breaking these down naturally at a much more controlled rate)
This is where your thinking, hold on a second, this joker has said in previous posts that phosphate moves from high concentration in the substrate (phosphate loading) to low concentration in the water column, so why wouldn't the phosphate just diffuse straight back out of the substrate and into the water column and be removed.
Well, remember that cyano needs a way to harvest these nutrients, and have ever seen cyano floating around in a marine tank in the water column? (unless you've knocked it off and stirred it up) Don't bother answering, the answer is NO.
Cyano harvests nutrient directly from substrates and rock, this is why it causes so many problems, and why it is a such a big problem in systems with phosphate loaded rock.
In the case of this tank with the wavemaker pumping water through the substrate, yes the phosphate should bind to the substrate and then re-release into the tank, and the organics should break down, and then be released into the water column, but a combination of the two releasing from the substrate at far accelerated rates, along with there not being quite as much flow in tank as we would like, has allowed the cyano to harvest this nutrient directly from the substrate water interface, capturing these nutrients first before they can be removed by the filtration.
Before I start describing how to combat this problem It should be noted that you first have to diagnose what the cause is, as we have done above. Get an Accurate set of test kits and collect some data on nutrient levels and your other tanks parameters levels as well.
In the case of phosphate loaded rock, this will be confirmed by the use of phosphate absorption resins, if you place a phosphate absorption resin or media in your tank (especially something like Seachems Phosgaurd, and activated alumina product that is incredibly aggressive at removing phosphate) and your phosphate doesn't change, or indeed actually increases, it is a good indication that you have phosphate loaded substrate and rock. As the phosphate is removed by the media, the phosphate in the rock diffuses from high concentration (in the rock) to low concentration in the water column that the media has stripped phosphate from.
Combating cyano
There are a few simple things you can do to get rid of cyano in your aquarium, but you need to eliminate the nutrient first. I have gone over organic carbon dosing and Nitrate limitation in a previous post HERE so if you need information on nutrient dynamics I would recommend also reading this before going any further.
First of all let me point out, things are going to get worse before they get better, much worse in some cases, make sure you have water mixed, on hand ready for water changes. It can be a bit of work but this is your reef tank punishing you for not being diligent in controlling nutrient, harsh but unfortunately true, but its an easy fix (relatively speaking) so don't get too upset about it.
1. Manual removal
Because Cyano harvests and actually stores nutrient for later use, syphoning off this nutrient will result in the removal of a lot of nutrient, as well as letting more nutrient leach from the substrate for removal. In a way, the cyano is actually helping you out a bit here, kind of, but we all still hate it and it deserves to die so syphon it out and show it who's boss. Make sure you remove as much as you can with a syphon hose, trying your best not to stir it up in the water column, and also being careful not to suck up too much of the substrate, however, it is easier to replace a bit of sand than rip a tank down completely (which i have done, and it ain't fun) so if you do, you can easily put a handful of new sand into the tank. You can even run it through a net or similar capture device to catch the substrate but wash the cyano off.
Keep doing it as it appears, over the course of the tank's nutrient reduction.
2. Removal of as much of of the nutrient, and stored nutrient as possible
This means not only getting rid of the phosphate and nitrate (through water changes, phosphate absorption resin/media or organic carbon dosing) but also detritus. As i just mentioned i have actually ripped a tank down and set it up again in the past, to remove the bulk of the sediments and nutrient from the tank to "get ahead" of the nutrient cycle. This essentially involved taking everything out of tank, saving about 30% of the water, cleaning the rock without causing too much havoc, stirring up the substrate and syphoning as much sediment and detritus from the system as possible., then cleaning the foam and bio media in the tank water to remove the detritus, syphoning every possible nook and cranny, cleaning the pumps and skimmer, and then placing all the rock back in the tank, with the corals and fish and filling the tank back up again. And the starting a very aggressive syphoning, and organic carbon/bacterial driven nutrient removal regime.
In this case, I was adding HUGE amounts of nitrate to drive accelerated phosphate removal from the rock and substrate, to the point where i was adding 10mls morning and night of Seachem Flourish nitrogen along with 15-20mls of NO3:PO4X organic carbon a day to a 250 Litre tank.
Even at this rate, it took around 3 months to get to consistently low nutrient levels, and was progressively backed off over that time period, to the point now where it is sitting at 0 nitrate and 0 phosphate as well. And i am still adding nitrate (in the form of seachem flourish nitrogen) every day, to the tune of 3ml. for consistent removal of nutrient
My point here is, whichever method you choose, its going to be a long road, so be prepared, organic carbon dosing i have found is a lot easier and cheaper than media based phosphate removal as you have nitrate removal AND in general it costs a lot less per unit of phosphate removed.
As a side note, I also have another person I know who i am helping with the exact same problem (phosphate loaded rock) and they were and still are running, organic carbon dosing (with nitrate dosing), a refugium (dosing with iron) which is growing at a rate that needs trimming weekly, HEAVY TRIMMING, and ROWAPHOS, also Phosgaurd at one point, and is only starting to see results now, after around 5 months. At one point soon they are going to have to decide which method of nutrient removal will be the dominant one and at that point shut down the others. but that is another story altogether, the point is, this problem can get VERY out of hand.
What i will point out is, re-scaping a tank and doing such a large overhaul should really only be done by people with experience in this area, or if your are confident enough doing it yourself and have been involved in the hobby enough to know you can deal with the possible reactions that could ensue. If not, just vacuum the substrate as much as possible (unless its a deep sand bed, then your in a bit of strife because it is most definitely not as easy).
3. Maintain skimming
Clean your skimmer and clean it often, every day to second day, and i find cleaning it in water from the tank helps it gets back up and skimming quicker, especially if cleaning daily. Your skimmer is skimming off nutrient, especially in an organic carbon driven nutrient removal situation, so keep it operating at peak performance, and if you have a skimmer that you feel might be underdone, go and invest in a decent skimmer, the best you can afford, that is correctly sized for your tank.
4. KALK!!!!!!!!!!!!!!!!!!!!!!!
If you have read my post on Maintaining pH you will know why I like this supplement so much, but in short, A higher pH will eradicate nuisance algae, as well as the Kalkwasser will also precipitate phosphate. Go down to your Local Aquarium/Pet store, talk to someone who knows how to use it, Buy it, put it in your top off, make a dosing system, shot it in a slurry...... it doesn't matter how you do it, just get your pH up there, monitor it, keep it above 8.4 (while testing your Alkalinity and Calcium so you don't overshoot) and it will most definitely help you get over this issue faster. if you would like to read the post on Kalk and increased pH you can HERE
5. Be Vigilant
You have to be committed to getting rid of this stuff, otherwise your never going to get anywhere.
6. Maintain lower nutrient levels and good husbandry
Make sure you keep your nutrient levels low consistently (and all water parameters stable and where they should be) and practise good husbandry. Your tank will thank you for it, and you will be a lot happier. This is not a part of the Aquarium keeping hobby that you can achieve good results in without work, unless you can pay someone to come and maintain your tank, be prepared to do some work, and you have to be committed to your tank.
.................... And then
A new beginning for your tank!!!! You can get down to business of growth, colour and chemistry, and start developing the tank you wanted.
I have been through this exact thing with three different tanks and it isn't easy, in fact its frustrating as hell, but the results are incredibly satisfying.
Know your path, and follow it, and you will be rewarded.
