Nuisance Algae: Bryopsis

Of all the nuisance algaes, bryopsis is just one of the worst.  Practically nothing eats it in large quantities, it takes over everything, and it can grow in just about any aquarium, regardless of nutrient and light levels.

Bryopsis looks like long feathery strands of green algae, and short clumps of it can sometimes be confused with green hair algae. 

In order to prevent algae, a good quarantine and dipping procedure is a great start.  By removing coral bases and treating any remaining non-coral areas with hydrogen peroxide, most nuisance algae infestations can be prevented.  Add in at least a 30 day quarantine period to watch for algae growth, and the chance of infestation drops further. 

If you find yourself staring at a mat of feathery bryopsis, have no fear…Tech-M is here!  Sorry, I couldn’t resist.  Anyway, several years ago a few aquarists discovered that by slowly raising magnesium levels in the aquarium with Kent’s Tech-M, the bryopsis just wilts and dies away within a few days.  However, before going nuclear on an aquarium, I recommend all aquarists first double-check their reef tanks for the standard issues.  This isn’t a waste of time – it’s just a basic checkup to ensure there’s nothing obvious going on. 
1.        Test the main aquarium parameters (ammonia, nitrite, nitrate, salinity, temperature, pH, alkalinity, magnesium, calcium, and phosphates).  If one or more is out of range, bring it back within range and keep it there for at least a week.
2.       Clean…everything.  Clean filter socks, sponge filters, skimmers, powerheads/pumps, siphon out the dead zone areas, blow the detritus out of the rocks, clean the glass/acrylic, scrub the rocks clean of algae, and siphon out as much algae as possible.
3.       Change all light bulbs (if not running LED’s) to make sure they haven’t started to shift spectrum.
4.       Perform a couple water changes with RO/DI – mixed saltwater, taking time to siphon out as much algae as possible. 
5.       Run carbon and granular ferric oxide (GFO) to remove any remaining gunk.
6.       Run a refugium with macroalgae on a reverse photoperiod to help with excessive nutrients.
If the aquarium is truly clean and a last-ditch effort is required, Tech-M may be the solution.  As far as I’m aware, no one has isolated what exactly in Tech-M causes the algal deaths, but it works when generic or other brands of magnesium supplements do not.  I tried the Bulk Reef Supply Magnesium Chloride in conjunction with pharmacy-bought Epsom salts (Magnesium Sulfate) with no luck while the Tech-M worked.  So, in order to treat, I recommend a huge bottle of Tech-M and a good quality magnesium test (I use Salifert).
Here are the basic steps:
1.       Day 1:  Test the aquarium water for a baseline magnesium level.  Remove carbon, GFO, and the skimmer cup so that the Tech-M can work fully.  Follow the bottle’s instructions on how much to add to raise the magnesium by 100ppm (no more per day.)  I prefer to use my favorite online chemical calculator.  Replace the skimmer cup after about an hour.  Many people dose Tech-M without removing the skimmer cup, so it’s not required. 
2.       Monitor the aquarium for any adverse changes.  Have saltwater pre-mixed in case of emergency.  Bad signs with this typically involve dying invertebrates (crabs, snails, etc.)
3.       Day 2:  Test the aquarium water again and add enough to raise the magnesium by 100ppm.
4.       Day 3+:  Repeat testing and dosing to raise magnesium by 100ppm until the bryopsis begins to die or up to 1600ppm.  The level required seems to differ based on the starting magnesium level, but there is not a direct correlation (most people have die-off starting around 300-400ppm above the baseline).  Going above 1600ppm is sometimes required, but it is more risky.  This is where having pre-mixed saltwater ready for a water change is a really good idea.
5.       If you use Salifert, like I do, the Magnesium test kit stops at 1500ppm.  If you need to go up to 1600ppm (or higher), it’s easy.  Test as normal, so a full 1ml syringe equals 1500ppm.  Refill the 1ml syringe, and keep adding drops until the reagent water mixture changes.  Note the level on the second syringe.  If the second syringe reads “0.90”, then the magnesium concentration read across is “150ppm”, but it isn’t really.  It’s 1500ppm from the first syringe added to the 150ppm from the second syringe.  The total magnesium concentration is then 1650ppm.  This extrapolation can be applied to many test kits available to hobbyists.
6.       Once the bryopsis starts to die, keep dosing to maintain that level.  So, if the bryopsis started to die at 1550, maintain the magnesium at 1550.  Although many aquarists say two weeks is required (or that dosing can immediately stop), I prefer a full month (yes, I know testing daily is a pain).  Many people, including myself, have experienced how bryopsis can come back in full force and seems somewhat Tech-M resistant if it is not treated entirely the first time.
As last thoughts, trace copper impurities are believed to be the main active algaecide in Tech-M, but it may be working with heavy metals such as lead, zinc, etc. as a more powerful algaecide (source:  HighlandReefer on ReefCentral).  Although the science behind Tech-M working on Bryopsis is well beyond this thread, I hope this helps someone start in the right direction.  Best of luck!!

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  1. Nuisance Algae: Bryopsis - Manhattan Reefs

    […] Nuisance Algae: Bryopsis I have some Tech-M on the way but have a question about when to start treating. My skimmer is way overpowered for my tanks (Tunze 9020) so as per the suggestion of Roger I am taking one half offline. Also I just got a dual reactor that is being cleaned as I type. Instructions for treating the bryopsis say to take simmer and reactor offline during treatment and recommends treating for a month. Should I run the skimmer (new single side setup) and reactor for a while before treating to get the tanks as 'clean' as possible before taking offline? Also should they be offline for an entire month or should I run either/both periodically? Link: http://www.reefdup.com/2012/02/23/nu…lgae-bryopsis/ […]

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