This is the log of the talk I gave on Algae on #reefs a few weeks ago. #reefs have not posted it yet but someone who saved the entire file was kind enough to send me the text of it.

The actual text below is an expanded version of the chat. I have added quite a few information to clarify some points that were made and questions that were asked. As such this document is far longer than the log of the actual chat that took place.

Good evening everyone, and thanks for being here tonite. It is a pleasure to address you on algae and answer some of the questions you may have. I know time is limited so we will not have the opportunity to cover algae in great detail, but I hope to bring you a better understanding of some of the basics you should know about algae in general.

Mention the word algae and hobbyists are likely to cringe. Indeed, at some point or another we all have had bouts of problems with micro-algae, cyanobacteria, slime, hair, filamentous, patchy, and whatever other form undesirable algae may take on.

We may also have experienced the growth in our aquariums of higher forms of algae, whether green, red or brown ( Chlorphyta, Rodophyta, Phaeophyta ) and, of course in reef tanks we all have coralline algae growth ( Corallinaceae ).

The appearance of undesirable forms of algae is, nowadays, much better understood and countermeasures of different forms can be taken to prevent from them from appearing, and eradicate them when they are already there.

I will be glad to elaborate on some of these during the question and answer period.

Whereas the "chat" is about algae in general I would suspect that most hobbyists are really interested in micro-algae and not so much in macro-algae. Some may have an interest in coralline ones too, I would suspect.

Questions about macro-algae are welcome though as, indeed, our corals can be impacted by the presence of too many macro-algae in the tank, or by their closeness to corals. Some macro-algae release toxins in the water and these toxins can affect corals, especially in smaller aquariums when the amount of macro-algae is rather substantial.

Additionally, authors such as Peter Wilkens and others suggest that exudates from may other macro-algae may be harmful to certain of the more delicate corals. This is especially so if your protein skimming is not removing these toxins from the water.

Carbon (activated variety for aquarium use) can be used from time to time to remove such exudates as well. The problem with prolonged use of carbon, and its possible side effects resulting in too large a desirable element removal, is not the topic of this chat, but is certainly to be considered if you decide to rely on activated carbon to purify the water more.

Should you have questions that I do not have an answer to during this session, I will gladly look the answer up for you. I have, over time, accumulated probably close to 100 books on all forms of algae. One would imagine that I should be able to come with an answer for you from all that material.

The term algae is so all-encompassing that it is not possible to have answers to all questions, even if one has spent a great deal of time reading and studying algae forms in general. There are just too many varieties.

To do I will need you email address of course. You can Email me if you wish .

Another area of interest that has lately been the topic of message exchanges on many Internet Lists is coralline algae. You are welcome to ask questions about all of these types of algae.

I will attempt to answer your questions as well as I can. Please understand that phycology (the study of algae) is a vast area to say the least, and I do not have all the answers either. Your understanding is appreciated. Hundreds and hundreds of books have been published on the subject of Chlorophyta alone (just to give you an idea of the vastness of the topic).

I have spent lots of time reading and learning about all forms of algae but what seems to be happening with knowledge is that the more we know, the more we realize how little, in fact, we do know. This certainly applies to my knowledge of algae and phycology in general. When one starts to delve into a particular topic in depth, one finds that one book leads to another book to yet another and so on, and that just to understand and be knowledgeable about one area is, indeed, a daunting task.

Rather than have a long introduction I would like to go to the question and answer time so we can cover as many questions as possible.

Note that authors differ in the recommendations they make. The opinions expressed here are mine and only mine. I relate what I have found but that certainly not mean that I have the magic answer for everyone. Just wanted to clarify that.

The main reason for not going into any detail in this introduction is because many of you already know quite a bit about algae, and I did not want to post material you are already familiar with. I decided that it would be better to answer questions.

Note though that if you are not, and you wish to ask a question about what may seem basic, go ahead. There are no questions too basic not to be asked. Indeed, some who are newer to the hobby may have far less experience with algae in general than those who have been in reefkeeping and in the saltwater hobby for a while.

If you need an answer, post your question to the moderator please. Any question if fair game. Let us try to confine it to algae though until after the chat is over.

I have a nasty cold but will try to stay on as long as I can. I spoke to Eric on the phone and he heard how bad I sound. I had comitted to giving this chat so here I am with or without cold.

Note also that if you wish to continue discussing algae you may want to join our mailing lists and post questions there. We have several mainling lists that are very active and where the level of information being shared is really of high quality.

To join our mailing lists, all you need to do is go to our web page http://www.athiel.com and click the button at the top, that represent the link to the document that describes how to join.

We know start the question and answer part of this chat.

<Saltman the moderator> Question: If I brought my pH down to 7.8, slowly, would this kill filamentous hair algae?

<Albert> With this short introduction over, I am ready to take your questions. Please note that when my answer is over with, I add my initials "AT" to the end of the line. This lets you know that my answer is over with to that particular question.

<Albert> I am ready to take your questions. Thank you for being here. It is a pleasure for me too.

Thank you to #reefs for reinviting me to "chat" so soon after my talk on lighting a few weeks ago. I appreciate the confidence and trust. AT <Saltman> Question: if i brought my pH down to 7.8,slowly, would this kill filamentous hair algae? <Albert> No not necessarily because when you change parameters slowly the algae adapt and most of them remain and do not die off. They may not be visible as the obvious ones may have died, but many spores remain in the water, ready to give rise to new growth as soon as conditions become propitious again.

The key is not to deal with the effect (the algae), but with the cause that makes algae grow (the phosphates and/or the silicates that are present in your water and constitute the nutrients needed by algae to grow)

Lower these nutrient levels so algae have none to feed on and grow back in your tank. This may require testing to determine their levels and then taking appropriate measures to lower both the phosphate and silicate levels.

Water changes and the use of compounds that remove them from the water are the generally recommended methods to accomplish this.

Depending on how high their levels are, several treatments with such compounds may be necessary. One or two treatments may not do it in all cases. Of course, you can monitor by testing, the levels of nutrients that are still in your aquarium and from that determine whether further treatments are needed.

In many cases, if algae growth is really getting out of hand, it is not uncommon to have to perform 5 or 6 consecutive treatments, a short intervals to deal with the levels of phosphate and silicate.

You can check articles in the saltwater library of our web site http://www.athiel.com to gain more information on how you should proceed. There are some real detailed articles in that library, and all are free for your viewing and downloading for future reference.

We also have a restricted, membership-only area, called the NetClub ™, where after you join the Club, you gain access to a whole series of specialized and detailed articles on many topics. Check our web site for more details by clicking on the NetClub ™ banner on the main index page.

<Albert> the other problem I see with changing parameters in the tank is that stress may be created and that can affect the animals in the tank and lead to problems of another kind that are hard to deal with especially in reef tanks.

My suggestion therefore is to look at the nutrient levels and do what is necessary to lower those, so the algae that are there already start to die off and that no new news grow. Remember that, in addition to water changes and the use of phosphat and silicate removing compounds, siphoning out any algae that die off or show signs of dying, is good way to speed the process up.

Indeed, all the algae you siphon out cannot decompose and, therefore, cannot add more nutrients to the water. If this were to happen the algae that die or died, provide more nutrients and these nutrients are used by new batches of algae for growth. Siphoning out what can be siphoned out is, therefore an excellent manner to speed undesirable algae eradication up. AT

<Saltman> Question: I want to know if there is a way to accelerate coralline growth in the reef tank? My coralline is growing very slowly, but my SPS corals is growing very fast!

<Albert> Often coralline algae require some of the same elements in the water as some of the corals that do well in your case the SPS ones. Calcium is of course the most obvious ones of these types of elements, but others are needed as well.

Perhaps what you may want to do is to increase the calcium levels and also the strontium levels and then use a complete additive at recommended dosages to speed up the growth.

Alkalinity plays an important role here too and you need to ensure that your alkalinity is not only at the recommended levels, but that its make up is skewed too far towards bicarbonates.

It has also been postulated that magnesium levels need to be monitored and maintained at NSW levels of 1300 to 1350 ppm. You may need a magnesium supplement to accomplish this. Alternatively, there are buffers on the market now that offer two part solutions that contain everything that is needed to maintain a proper alkalinity and magnesium levels.

I have rarely seen potassium levels go out of balance so that should not be a concern.

Water changes help a great deal here as well as they are a way to replenish missing ones, or diminished concentration of certain needed chemicals and elements. Use a high quality salt for your tank, and try to establish through testing that it is high in calcium and magnesium.

This sort of leads me to stress how important it is to test your water, especially in the beginning. Once you get a good handle on what you need to add to your tank on a regular basis, you may be able to test less frequently but in the beginning you certainly need to test every few days and establish what kind of elements that are important, diminish and to what degree. This in turn allows you to determine what and how much of it you need to add to balance the water quality parameters out. AT

<Albert> Temperature may also be something to look at as you may need to increase it somewhat as well. The present recommendations are generally to keep tank temperatures at 79 to 80 degrees F. Note that some authors recommend higher ones than that.

Ron Shimek is one of those and you may be familiar with his writings. Whether we want to really go that high (85 F or more) is still being debated by many. Results appear to vary depending on what type of corals you maintain. In my opinion this is an area where more research is still needed.

Recently on our mailing lists, extensive discussions took place on tank temperature. You can access the logs of those messages on our web site by going to the database search link and using the keyword temperature.

This database is huge and you can conduct searches there for so many topics that they are too numerous to list. Check the search engine out from time to time and you may be amazed at the amount of valuable information you will find there.

So to recapitulate: there are many variables involved and it is not easy to diagnose without having a set of tank parameters why your coralline algae are not growing as rapidly as you would like them to. Use the guidelines given earlier and test and then adjust what needs to be adjusted is the best advice I can give you.

<Saltman> Question: Could live sand that was added to the tank over a year ago be the cause of red, green/black and hair algae

<Albert> I doubt it honestly, but then there may be some organic material in that sand and that organic material is dying off, giving rise to dissolved organic material (DOC) and small amounts of PO4 and SiO2, just enough though for algae and diatoms to grow

Additionally, and this is a controversial topic, if you are running a plenum on that tank, the amount of nutrients that accumulate in the plenum may start to leach back into the tank by osmosis, or through the sides of the grids that support the sand, close to the tank panes, if the separation between the plenum and the tank itself is not water movement tight.

When that happens a continuous stream of nutrients enters the tank, and unexplained algal growth starts. This is a difficult situation to remedy as the stream of nutrients is continuous and thus the supply of foodstuff for algae is also.

Again the saltwater library of our web site contains a rather detailed article on this. The Netclub ™ contains an even more detailed one.

There could be another explanation too. Say that you have live rock and that some areas of that live rock are covered with material of organic nature that starts to decompose.

This decomposition lowers the pH in that area. Indeed it goes hand in hand with the production of carbonic acid (carbon dioxide first and then carbonic acid as it mixes with the tank's water).

If, now, in that same area there is precipitated calcium phosphate, this calcium phosphate will redisolve because of the low pH in that area (due to the carbonic acid) and will result in the nutrient necessary for algae to grow in that area.

That is the scenario where you measure your water quality and everything seems fine, yet algae grow in some areas anyway. The reason everything appears to be fine is that the phosphate and silicate are used up immediately in those localized areas by the algal growth that occurs there.

Remember too that what you measure if actually what is left in the water, after algae have helped themselves. If you keep that amount real low, the algae will not have enough nutrients to survive and their numbers will start to go down. Eventually all of them disappear because the nutrient level is too low to sustain any growth.

The above expalanation could very well apply in that case. The key therefore is to keep the rock and its pores and crevices clean at all times so that this scenario cannot occur.

This is done mainly by creating a lot of current and turbulence I should say. Such high current prevents the rock from loading itself and prevents the formation of areas where this could happen. Preventing the redisolving of phosphates into the water in localized areas, prevents the growth of undesirable algae in those areas, and in the tank in general. Current and turbulence are more important than we think.

<Saltman> Question: is there any reef safe critters that will eat bubble algae(valonias) <Albert> Some herbivores do but IMHO Valonia, one example is the Red Sea desjardini Tang. It would appear that the Indo-Pacific variety of this Sailfin Tang does not consume this bubble algae.

Valonia is best removed with tweezers as soon as one sees it appear and before things get out of hand. Be careful not to crush them, as when you do you add plenty of spores to the water and new ones will start to grow in other areas and you will have a larger problem than you started with. AT

<Saltman> Question: What is the cause of cynobacteria?

Wow, that would take a whole chat in itself to answer. There are three long articles on our web site in the SW library that detail why cyanos appear and explain how to get rid of them. I suggest you go to our web site and read those articles. They are very detailed. You can access them at http://www.athiel.com

in short though when organic levels (DOC) or dissolved organic carbon starts to build up in the tank and that goes combined with the right te> hting certain types of cyanos appear. Their growth can be real slow at first, and spotty. Soon though you have them everywhere. Your best bet here is to go to our web site's saltwater library and read the articles that I have posted (there are at least 4 or 5 long and detailed ones). AT <Saltman> Question: Are supplements that contain yeast a good way to feed corals? Im concerned the yeast would encourage algae growth

<Albert> Used in moderation and with adequate skimming you should be able to adjust the level or amount you add so that no side effects occur. Bacterial blooms may occur as a result of adding the yeast but are usually short lived, especially if you adjust the amount you add.

Close observation of what happens in the tank is therefore necessary. If you find that your water clouds for too long, you may need to lower the amount you add. Of course not all corals benefit from this type of feeding. Many do and the method appears to be gaining popularity.

The answer is yes it is a good way to feed and yes you need to be careful with quantities as it is easy to put in too much and end up with algae and/or bacterial blooms.

However the proof is in the pudding as is said, use a certain amount and if you find that you see algae appear start diminishing the quantity you add.

In respect to yeast there is another benefit, it helps the reduction of nitrates by promoting the proliferation of bacterial growth and the reduction of nitrates as I have indicated a number of times on our mailing lists and in articles on our web site. In that case I have recommended the use of Brewer's yeast. AT

<Saltman> Question: Does Vital Gold have enough strontium or should more be added? Not really an ALGAE question

<Albert> It is fine to ask the question though tough. More info for those who are here and for those who will read the logs afterwards.

Yes it has for tanks that have mostly what we would call an average load but, as soon as you go towards a high load then you will need to supplement with more Strontium, either in the form of a strontium additive or by using our KSM (see our web site SW library for details on this product).

The higher the load the more this becomes necessary. Note that strontium levels can be monitored and tested and adjusted to match natural seawater levels.

KSM is used to add not only strontium but a large number of other elements as well, as explained in the document on our web site in the SW library under Product related articles. It has been mentioned many a time by hobbyists who use it that they have not had any problems with RTN (rapid tissue necrosis). I do not have any scientific explanation for this but, for sure, a lot of anecdotal one from messages from hobyists who report this fact.

<Saltman> Question: Are there any good references for identifying macro algaes?

Yes, sure there are.

The books by Ann Harbor Press by Dr Randolph Taylor are used in just about every lab that deals with algae and are the standards in phycology. Those who wish the exact titles and details can email me and I will be glad to send them more info on good books dealing with all categories of algae. AT

<Saltman> Question: What should be the first steps involved in trying to elimate the red slime/green/black and hair algae?

<Albert> What I would do first is siphon out as many as you can, and then perform a sizeable water change making sure that the water you add is of the same water quality parameters as the water in the tank.

Then I would check the DO (dissolved oxygen) and the BOD (Biological oxygen demand) and see if you have a high amount of DOC (dissolved organic carbon) level.

IF this is the case I would consider using a strong oxidizer to lower DOC, or continue to use water changes but what you do should of course not end there.

You need to find out why they started to grow to begin with, and where the nutrients they thrive on are coming from. As you lower the nutrient level, more of them die off, and you siphon out more of them out of the tank, continue doing so either with water changes or a combination of water changes and the use of an oxidizer

Keep siphoning what you can siphon out, and keep using the oxidizer to reduce DOC.

Soon you will be down to a level where the algae do not grow again and you have solved the existing problem.

Next, you will need to figure out why the DOC was high in the first place and remedy that situation. The Saltwater library of our web site contains several articles on this too. You may wonder why I keep refering to it. Simply because there is so much information there that it pays to go to our web site and read all those articles. AT

<Saltman> Question: Micro algae is going to be present in any system, where do you personally draw the line as to being a nuisance

When it starts to get in the way of what I try to achieve in the tank that is keep the corals healthy and growing.

When I see algae in areas that may be a threat to a coral, then I know that intervention is a must.

I could use hermit crabs and snails if the problem is small and keep things under control in that manner. Having some blue legged hermits in your tank is not a bad idea anyway since they will control small amounts of algal growth. Do not put too many as when the food supply runs out, they will start to die.

Some of the red legged varieties can be used as well. Careful though as there are types that become rather aggressive when the algae supply runs out. They may attack your snails and other small animals and may even attack each other. The Mexican Red Leg is famous for doing this. AT

<Saltman> Question: Is there any easy way to tell if algae is good or bad? i.e.-dusty and slimey types are bad but what about branchy and leafy looking algae are they always good?

<Albert> Hard to answer without ID of the type of algae it is could be good could be bad or could be indifferent really.

Before deciding whether it is a desirable one or not, one needs to know what one is dealing with, and then determine what needs to be done with respect to those algae if they are considered undesirable (this applies to all macro-algae too, of course, as too many of them can be detrimental to corals and can cause damage, or can cause them not to open up but. Again it depends on the type.

The difficulty one runs into is that some of the algae one finds in aquariums are not always easy to identify, especially not from a description in an email message. Not knowing what one is dealing with, makes it difficult to generalize and make a recommendation that applies to all situations. AT

<Saltman> Question: Have you eradicated dinos by lowering salinity?

No I have not tried doing it that way because I do not like to change the chemistry of the tank each time something needs to be dealt with. Such is in my opinion not good for the tank and not good for the animals. Stable conditions is what I strive for.

I use the method explained ealier. I use water changes and mild oxidizers combined with siphoning out what I can until I have things under control.

Mind you in a well managed aquarium that is monitored regularly one can usually catch the problem before the dinos or cyanos show up. Again regular testing of the water quality parameters is what is suggested. AT

<Saltman> Question: With 4" of live sand as substrate should I stir this up (due to not having anything else in the tank to do it) so that algae dosnt grow in it?

<Albert> If you have no sand stirrers then you do indeed need to find a way to keep that sand moving. This can be done by stirring it or by adding the required sand stirrers. Note that outbreaks of RTN have been attributed to the fact that sand layers are being stirred and that Vibrio (which is attributed at this time as the cause of RTN in SPS corals, is thereby released in large amounts in the water.

The way this appears to affect the corals is as follows: large numbers of Vibrio bacteria colonize an SPS coral and attack it. If the coral is stressed and not doing really well tissue necrosis may set in. This is a very extensive area and it would take a whole chat to discuss this in detail though.

It is however to the point as RTN is becoming a problem for many hobbyists who house SPS corals in their tanks. My personal belief is that a nutrient or chemical element deficiciency is at the root of the problem. The RTN sets in as a secondary symptom after the massive attacks by Vibrio bacteria. AT

<Saltman> Question: does increasing the pH to 8.4 (according to D&S) really reduce the dinos? <Albert> Yes that is correct but that should occour naturally in an aquarium that aged well and is running well where a pH fluctuation of between 8.2 and 8.4 is usually the norm. Note in this respect, that your skimmer functions better at higher pH levels too. AT

<Saltman> Question: Are diatoms detrimental to the reef tank?

<Albert> Good question. Depends where they grow and whether they are encrusting or not.

If they grow on coral skeletons they are detrimental for sure and may result in tissue receding. The diatom grows upwards and prevents the coral polyp from remaining attached to the coral skeleton.

If they grow elsewhere they may not be detrimental, especially if you are not too fussy about the aesthetics of the tank. After a while though, when the amount increases, you may wish to intervene and use silicate removing compounds to lower silicate and silicic acid in the water. This will result in the diatoms slowly disappearing. I strongly recommend this method as I am always suspicious of any diatoms in the tank as they can cause havoc with both SPS and LPS corals.

Algae is something that we all deal with and that does not always require total eradication (which may not be possible anyway) but careful management is a necessity in my opinion so things do not run out of control. The more algae and the more diatoms are present, the more difficult it becomes to remove them from the aquarium and the costlier it will get to do so. Prevention is the best approach. AT

<Saltman> Question: Can lighting that is getting old cause a buildup of hair algae, as well as lightening of corals?

<Albert> Yes certainly but only if the nutrients necessary for algae and diatoms to grow are present in the water already. While the spectrum of such an older light may promote algae growth as it shifts towards the yellow and red, unless there are nutrients in the water, algae cannot grow. Light is only a catalyst. Nutrients (phosphate and silicate mainly) need to be present as well.

If you were to put 10 000 watts over a bowl of absolute pure water nothing would happen because their are no nutrients for the algae to grown on. Light is a catalyst not the food for algae. AT

<Saltman> Question: Are there macro-algae eaters, other than tangs, that are 'reef safe'?

There are plenty of urchins that will eat macros but whether you consider them reef safe is another matter. Indeed they can damage corals with their spines.

Other algae eaters include some of the gobies and some blennies and even some of the real small wrasse. Of course hermit crabs need to be considered too as they do an excellent job at cleaning the tank of algae and so to many types of snails. AT

<Saltman> Question: I've heard different opinions in regards to what appears to be green coralline in my tank. Have you heard of this before, and is it due to inadequate lighting?

Green coralline is probably some form of coralline overgrown by a form of diatom whose growth is promoted by the presence of silicates.

There are very few green coralline algae although I have run across several species. Most hobbyists do not see them in their aquariums though, or rarely is maybe a better way of putting it.

Keep the silicate levels below 0.5 ppm and you should have no diatom problems. AT

<Saltman> Question: Are diatoms necessary for turbo snails and astrea snails to live?

<Albert> No, all they need is algae AT

<Saltman> And our last question belongs to Guitar: how do I get rid of a daily buildup of green algae on my glass!

<Albert> you probably have a level of PO4 that is higher than 0.03 ppm and that gives rise to the growth of small green filaments on the glass.

What you can do is the following: take a sponge and go with it to the bottom of the pane, wipe upwards and take the sponge out of the water and rinse it well.

Now go to the next area and wipe again from bottom to top and rinse the sponge again.

Keep doing so till the glass is clean.

Doing it that way does not put the algae you wipe off back in the tank where they will decompose and add even more PO4 to the water, which then gives rise to even more algae growth.

Once you have done that though, you will need to determine what is causing the persistent higher levels of PO4, and intervene to keep them low so algae cannot grow.

There are several articles on our web site in the SW library that you can read and that deal with controlling algae and diatoms and cyanos.

There are, in fact, three long articles on Cyanos that explain a great deal about why they grow, what varieties you may be dealing with and so on. You may wish to go there and read them. AT

<Saltman> Thank you Albert! Would anyone like to ask any final questions?

<Albert> The address for our web site is http://www.athiel.com

<EricEE> Thanks for coming Albert!

<Albert> Thank you.