Before going into the Q-A part of the "talk", below are some initial remarks to set the stage for the discussion.
Note that many have written about algae and that there is only one way to skin a cat so you will find both ideas you may know
and new ones in these short introductory notes
Algae becomes a problem whenever they take away from the "look" of the tank or, stated differently, from its
aesthetic and visual appeal. When too many algae are present (both micro and macro) they may interfere with the growth of
organisms because they will grow over and on them, thus "choking the coral or the animal. This is probalbly a far greater
problem that the former. Looks is one thing, but loosing animals is another one entirely.
Note that all forms of algae can lead to such a situation, not just the so-called micro and filamentatious ones. Macro
algae that overtake the aquarium will lead to the same consequences. In some cases even coralline algae can cause a problem
if they lower calcium levels too much and make it unavailable or too low for corals.
There really is no simple pathway, or approach, for controlling excess algae because a number of factors are involved.
Excessive levels of nutrient are in just about all cases the norm though, when algae growth gets out of control.
Nitrate, phosphate, silicate, carbon dioxide and dissolved organic matter are most often the cause of such growth. On
the coral reef they are very low in concentration, often near zero and in the ppb range. In the aquarium they typically build
up over time and thus accumulate, and become the basis for the appearance of filamenentatious, encrusting, and free floating
algae and diatoms as well as macro algae.
Controlling these levels by direct and indirect action is the key to eliminating this "problem". Direct methods
would include controlling the concentrations by various approaches directly, and indirectly by for instance reducing feeding
(a source of nutrients), maintaining low population levels and so on.
More often than not though, bioload is something most hobbyists do not deal with as they keep adding animals to the tank.
Dealing with the sources of nutrients directly is therefore a better approach in my opinion.
Let us quickly review some of the most important ones that we can use to do so effectively. Feel free to ask questions
about the various methods and suggestions given here.
Using a Protein Skimmer: Foam fractionation is used to reduce Dissolved Organic Carbon or dissolved organics (DOC). Use
an efficient model and make sure that the foam is dry and colored and smelly. Lowering dissolved organic material will in
just about all cases eliminate problems with red algae and will lower the CO2 in the system as well (and as with all plants
and algae CO2 is a major nutrient). Skimming eliminates matter from the tank before it can mineralize and increase the nutrient
levels. This is a step higher up in the sequence of events than say, eliminating the nutrient directly (e.g. PO4) and is therefore
a very efficient way to control nutrient levels by doing so before they occur.
Phosphates: Reducing and lowering PO4 is the one single most effective way of controlling most of the algae we do not
want. Phosphate is found everywhere in nature. Nutrient import paths include ( nutrient get in the aquarium) from a multitude
of sources: food, salt, carbon that leaches it, additives, and the raw water you use. R.O, D.I. and otherwise purified water
such as well, or spring water will make a large difference in the concentrations of PO4 found in the tank. Phosphate levels
should be at as low a concentration as possible. Recommended levels are in the 0.03 to 0.04 ppm. That is very low. Use any
means you can to avoid adding PO4 to the tank from sources you can eliminate e.g. the ones mentioned above.
Salts: Many salts contain phosphate and some fluctuate in their relative purity so it pays to test a bit of salt in some
water and get a reading before using the batch and adding it to your tank. PO4 tests for saltwater are not the same as for
FW. You need a Ascorbic acid based test such as the ones that are commonly sold or if you want a real good one, use the Hack
model PO-19 one. It is very accurate and reads below 0.1 ppm, a range you need obviously if you want to attain 0.03 or 0.04
ppm in your tank.
If green algae in your tank start to die off, make sure you siphon them out or they will add more PO4 to the water causing
other algae to grow. This is 'very' important or you will not achieve much progress as the dying ones provide food for the
next batch to grow.
Reduce Nitrate: Altough not the most important nutrient, combined with other ones nitrate will certainly lead to an explosion
of algae. Keep it low by using nitrate remvoing methods or higher algae in limited numbers and place corals in the thank to
help in this reduction (clams uptake lots of nitrate amongst others for instance). Remember when testing that nitrate nitrogen
levels must be multiplied by 4.4 to convert them to total nitrate. Suggested levels : as low as possible, realistically below
5 ppm total nitrate.
Activated Carbon: test all activated carbon you use. It is one of the main contributors to PO4 increases in the tank,
in conjunction with overfeeding. Use a little in a small amount of water. Let is soak for about 20 minutes and then test that
solution. If the carbon you have adds PO4, get another one. Good brands are the ones by Two Little Fishes, TAT (not related
to me anymore) and a few others sold in the hobby. Testing is the solution though to being sure.
Silicates: Golden brown filaments that show up on the the glass, sand rock and decorations are probably diatoms. Diatoms
need silicates to grow. The more of it is present, the tougher it will be to keep diatom growth under control. Water and salt
appear to be the most frequent sources. Control those and you should not have problems with diatoms. Remove silicate by using
a silicate removing compound for instance and by using RO or DI water on the tank and not tap water. Dying diatoms add silicate
as well so when you treat the tank for diatoms siphon the dying ones out to prevent them from adding more nutrients to the
tank for other diatoms to grow.
Lighting: The more red and green in the light spectrum, the more algae will grow if nutrient are present. Light does not
grow algae. Light is a very powerful catalyst though and with warm ligthing (low Kelvin degree range) and nutrients in the
water, tons of algae will grow. Cutting the lighting may reduce algae growth but does not deal with the root of the problem:
the nutrients. The only effictive control is to deal with the cause (the nutrients) and not so much the result (the undesirable
algae). Sure, changing the bulbs when needed helps, but only because the spectrum then changes and is not as warm. Keep a
high K degree spectrum and light will act less in the growth of algae even if small amounts of nutrients are present.
Lighting itself is not the cause though as I explained. The real cause are the nutrients we discussed
Carbon Dioxide: Vigorous movement of the tank water, powerful skimming aeration and current will reduce CO2 to levels
that are not acting as too much of a nutrient source. CO2 is necessary so it cannot be eliminated completely (could not be
done anyway) but it has to be kept low by adopting the above recommmendations (flow, current, aeration, skimming).
Coralline Algae: adding kalkwasser to your tank to increase the calcium content and adjusting the alkalinity to the range
of 8-12 dKH will promote the growth of coralline algae. This will in most cases prevent the growth of undesirable algae forms
if this technique is used in conjunction with the other nutrient control techniques described. KW is also said to help in
the control of PO4. Algae growth will occur if calcium is at recommended levels (350-450 preferably around 400 ppm) and when
alkalinity is high as well. Levels of 10 or higher dKH will result in more coralline algae growing than at lower levels (that
is why you get more corallines when you use two-part calcium/buffer compounds).
Algae Eaters: this is how John Tullock puts it: "Many species of marine life feed on algae, and some of these should
be in every tank. Tangs, angelfishes, some blennies, rabbitfishes, sea urchins, hermit crabs, and many kinds of snails are
in this category. These species will benefit from being able to graze on algae growth in the tank, and will keep the tank
from looking "overgrown." Some of these are better suited to smaller tanks, while others are more appropriate for
large tanks with many fishes. Still others are most useful in reef tanks. " This is certainly true and the addition of
animals that eat algae goes a long way to being part of the total algae/nutrient control picture and scenario. Talk to your
LPS to get additional input if you need it.
Using corals is certainly another way to control algae and nutrients. many coral export or uptake nutrients from the water.
This is a helpful adjunct to other methods used and is discussed in my new title: The Marine Fish and Invert Reef Aquarium
which will be released at the EPARC conference in PA in October (check their web site http://www.eparc.com for more details
or check our free web site http://www.athiel.com and use the search the site feature on the main index page to search by keywords
such as slime algae, phosphate, micro algae and so on.
Controlling algae in the tank is in the majority of cases a matter of controlling the nutrient levels and ensuring that
nutrient export occurs so that nutrients cannot accumulate.
Hopefully the above has given you some ideas on how to improve conditions in your tank.
Q & A
What color is the "GOOD" algae?
Depends on the species. Most good higher algae are green but there are red ones too. Corallines are usually red to
reddish and purple and calcareous algae such as Penicillus and Halimeda thend to be green also most other algae sp. that are
desirable will predominantly be green
Could you be more specific as to which corals one should look to for nutrient export?
Xenia uptakes organic material (DOC). Nephteid corals uptake green floating algae such as the real real small one
that we find in tanks. Gorgonians uptake particulate matter and small detritus. Soft stony, corallimorphs and Zoanthis uptake
just about all forms of nutrients
When all of these do not grow well in your tank it may very well be that the nutrient levels are too low and that
they do not get enough food, in which case you need to increase feeding and add specific foods for the types of corals you
In all cases adding such corals to the aquarium will help keep the water purer and less charged with nutrients thus
reducing the potential for undesirable algae growth.
Do you think that skimming can be eliminated completely when Mangrove filtration and live rock are used?
If you have sufficient corals and porous live rock in the tank and some live sand you can probably eliminate skimming
but there is a good way to do so ..
And that is to reduce skimming first and not eliminate it altogether but just skim less and less and see how the tank
does and adjust the amount slowly downwards after adding other nutrient uptaking animals or devices until you can eliminate
it altogether. Right now this seems more feasible in larger tanks and not so much in smaller ones where the amount of animals
per gallon is too high and the nutrinet levels may rise far faster and thus be detrimental
Altough possible it is not something that I yet advocate with mangrove
You can certainly look for a reduction in skimming but the number of mangroves and possibly seagrasses will determine
how fast you can do so
What are early indicators I'm getting a nuisance algae that isn't really easy to see, say a light coating of slime algae?
The early indicators are usually a lowering of the DO as these algae uptake O2 and that is an easy way to follow what
is goiing on in the tank. Yes a film on the glass is an indication too that algae are growing and rather than just wiping
them off and adding them to the water (which increases the nutrient levels so more algae grow) is is best to wipe them off
and rinse the sponge each time you have wiped a small area. Oxygen is however a real early indicator
Are there any good sites with pics, so I can ID a nuisance early?
Not really. Spread over many sites as far as I know and found in some books including the new NMFIRA and the books
by J Sprung and C Delbeek. Some specialized books also give more information that general aquarium books. I have tons of books
on phycology (algae) and even then have to go to several books to get a good overview
Maybe somebody should start one up (g)
Can live sponges be used to export nutriets out of the system?
Yes they can but the problem is that sponges are generally hard to keep and when they die off they really pollute
the water hence I do not really recommend them especially in tanks with lots of detritus floating around as that eventually
gets in the delicate areas of sponges and clogs the uptake channels resulting in die off and large amounts of pollution should
a large sponge die off. This is very hard to counteract as so much pollution is generated. Oh i forgot : clams uptake large
amounts of nitrates btw
I have noticed recently that the rather thick coraline algae that grows over the back of my reef has began to die or fall
off the glass in spots any Ideas what may cause this?
It could be that the new corallines growing on top of old ones make the older ones underneath die off due to lack
of calcium uptake as they are covered by new ones and when the ones underneath die everything comes loose and falls off That
is the most logical explanation for that phenomenon
I've got some brown sploches of algae growing on my glass, it is brown in colour and has the general shape of coraline.
I'm pretty sure it's not cyano, so can you pls help me id it?
Sounds like diatoms due to excess silicates in the water You can wipe them off by going from the bottom to the top
of a pane with a sponge, then rinsing the sponge, then wiping another area and rinsing again and so on. If they are not really
crusty my feeling is that you are dealing with brown diatoms
What are some of the best ways to combat Valonia? Have you had any personal experience with Emerald Crabs.
I usee tweeezers to get them out when they appear so that I do not burst them and add tons of spores to the water
which gives only rise to far more. With Valonia it is best to intervene right away and NOT let things get out of hand. very
few fish if any really eat them and other control methods such as crabs are iffy or dangerous for other animals in my experience.
Although Mythrax are supposed to be non-aggressive I have not experienced this to be the case so I shy away from them in favor
of the manual removing method I described
Is overfeeding the main problem and does feeding live foods vs prepared or frozen contribute to the algae problem too?
Overfeeding can be a problem indeed especially in tanks with not enough bio and other filtration. Feeding levels can
be played around with until one finds the right amount that does not lead to a build up of DOC and other nutrients Live and
fresh foods are far better as they add far less nutrients (especially PO4) to the tank than frozen food when i use frozen
food (rarely) I always let the fluid that ensues after thawing flow of the saucer I have the food in so that as little nutrients
as possible are added. Zoo plankton and Phyto plankton are probably the best
Other than a good skimmer and reduced feeding, what else should be done to combat a constant problem with red cyano/nitrates?
a good way to reduce DOC is to add controlled dosages of potassium permanganate diluted in water to the aquarium.
Use a 5 % solution and be very careful with the amounts added as KMnO4 increases the redox potential rapidly and that can
shock the corals and fish so you need to add a little of the liquid frequently so that DOC slowly gets oxidized and that cyanos
do not have enough nutrients to grow. Siphon all cyanos out when you see them. Do not let them get out of hand and do not
stop the addition of the KmnO4 too soon or you will not have achieved what you are trying to accomplish. It can take 5 to
7 days before you see a large difference but the diluted pot permang will do the trick for sure
Ozone is another way to go but that poses a problem in reef tanks as the corals will react negatively for pre-treating
or for injecting in the skimmer at low dosages though, it is another method that can be used. I have excellent success treating
tanks that have such problems when I do consulting work that I use the potassium permanaganate most of the time.
What is your definition of a 'smaller' 'tank as oppesed to a 'larger' tank?
(g) indeed ! Small anything less than 55. large 75 and over
Could u use mussels or oysters to reduce nitrates, instead of clams?
Yes you can but they are not as efficient and tend to die off sooner or become food for some fish IME
I don't mine some occasional valonia bubbles, and I read something you wrote about there being 3 different kinds. Mine
is pretty round, and looks like green glass. Feels like hard rubber. Any tips besides physical removal?
Add other forms of higher algae to the tank so that they are outcompeted. Caulerpa is a good choice and grows rapidly
if conditions are right. You can also increase the nubmer of coralline algae as that will help as well
What about dosing hydrogen peroxide to increase redox? Any guidelines on quantities?
No no not a good idea. Most corals react very negatively to the addition of H2O2 and several authors including Peter
Wilkens are strongly opposed to the use of hudrogen peroxide so I am afraid that is not what I consider a viable solution
although it sounds appealing.
Since clams reduce nitrates, does that mean that adding one to a tank with 50ppm + of nitrate would be ok, or is that
too high for them?
No that is not too high You can add a clam and just check the levels and you will see them go down
I was under the impression that you shouldn't mix LPS & Soft corals with SPS corals. Which of the mentioned nutrient
exporting corals can be safely housed with SPS corals?
As long as you keep a good balance you can mix the two without any problem. The difficulty comes when you have too
many of one kind though but if you keep a balance you can certainly do so. Saw a 15 gallon recently that had a nice mix..
You can use all of the ones I mentioned
Isn't there a certain percentage of H2O2 present in all water?
H202 is very short lived and breaks down quickly so there is none in the water in your tank.
Thanks to Albert Theil and Reefs.Org for this article!