Quote:
Originally posted by manderson0805
... I came home to find all sand in the open covered with a brown algae. There are also a few patches of a reddish algae, that is almost like a mat on top of the sand.... ...The tank had a brown algae problem for about 5 days, and is starting to bloom with coralline algae on the back glass. What else should I do besides siphon it out?
|
The coralline is part of the "next level" beginning to develop in you system. Cyano at this point is the earliest "plant type' organism in your tank to take advantage of the presence of nutrients in the water column. As the tanks diversity and complexity of life increasese, your problems with cyano will decrease.
As far as the Cyanobacter goes, I concur with the statement about Phosphate driving these blooms, but this is only one of the factors that influence blooms. Aquaria that have problems with cyanobacter species usually have a combination of not only chemical/nutrient problems, but also physical and biological problems varying from lack of competition for nutrients to too long a photoperiod. Usually all the factors that influence
Cyanobacteria spp. growth are present, but some increase in one factor can be the key to producing a bloom.
The chemical factors for cyanobacteria can have many sources, but usually center around the availability of nitrates or a nitrogen source (could be ammonia as easily as nitrite or nitrate, but usually nitrate and/or DOM in stable systems) AND phosphates. At this point you are addressing one of the main sources of phosphate, in your top off water, but other sources of phosphate are readily available in your inputs to the tank: feeding (especially flake), carbon from coconut shells or carbons treated with phosphoric acid (freshwater), and occasionally the salts for synthetic seawater mixes, although that practice has pretty much fallen by the wayside now. Many municipalities use phosphate additives to reduce the possibility of lead in drinking water. Older systems use polyphosphate resins to soften the water in areas where the raw water has large amounts of calcium present. It would be very important that you use some type of water purifier to remove these sources of phosphate. Please note that although many of the RO units have a rejection factor of 99% that often does not mean that it is removing 99% of the phosphate! Phosphate is a small enough molecule that the RO membrane cannot efficiently remove much of the substance. In many cases, you will find that the companies (check spectrapure's web site for an example) cannot guarantee that they will be able to reduce the phosphate level at all unless the water is further processed by a deionization resin column (i.e., RO/DI water), and even then, the level may be reduced by only 50 to 70% based on the input-water concentration of this ion.
I would try to limit the input of phosphates, but don't be so concerned with this that you feel the need to stop feeding your fish, rather, find a way to export the phosphate. There are many ways to do this, my personal preference is to use a refugium and grow macroalgae. This removes the phosphate as you harvest (and discard) the calerpa/halamida/whatever you grow to take up the phosphate.
Algal turf scrubbers do the same, although I am not a big fan of these systems. The use of a good skimmer is another way of removing these compounds, and it will reduce the levels of Dissolved Organic Materials (DOM), but skimmers will remove any phytoplankton and other particulate materials that are food sources for many of the tanks inhabitants as well. For new/i9mmature systems, skimmers are pretty much required to prevent these nuisance blooms for the first year to 15 months, after which time you can decide whether or not you want to go skimmerless. On this you need to make a decision on whether you want to develop competition for the resources or eliminate some of the overall problem by skimming. I personally have pushed my skimming to running only if the cyano gets a toe-hold, and I have not been skimming at all for almost 7 months now (on and off for about 4 years) with little or no
cyano BLOOM in the display tank (DSB, 6 years old, 6" no plenum)
If you are testing for nutrients and show little or none in the water column, keep in mind that if you have an established cyano growth, as soon as you are adding nutrients to the system the cyano will be taking them up. Another means of removing these nutrients would be to siphon up the cyano and discard it as part of your water changes. This not only removes the organism itself, but exports the nutrients that the organism has locked up as well.
As far as the aluminum oxide compounds go (phosphate sponges), I don't like them, although I have used them in the past. They have their own impact (high Aluminum conternt) on the water column, and
Sarcophyton spp. will let you know that they don't like them by either shriveling up and shedding a coat of mucous or dying, not what I would consider a good exchange for getting rid of the cyanobacteria.
There are physical parameters that affect the growth of Cyanobacter as well, long photoperiods and water circulation. Good water circulation inhibits the growth of cyanobacteria mats, and for mats to develop, there needs to be large amounts of light. These organisms are neither plant nor animal, but have characteristics of both. They contain a red chlorophyll-like substance that allows them to photosynthesize carbohydrates in the presence of CO2 and light, but they also have the ability to capture substances for growth through a diffusion process (active transport for this organism is fairly slow, but does play a role in its growth). Slow water movement increases the likelihood that the organism will be able to capture foods, as well as the likelihood that the concentration of nutrients will be higher in still water (diffusion, remember?). If you have fishes that like to resculpt the sandbed, they can cause still eddies in the substrate that will lead to small patch blooms, as well as exposing young substrates to the water coulmn that do not have a good biofilm yet (which will be cultivated by Cyanobacteria). Even worse, if the sand bed is still immature, it will cause a release of sinked nitrogen compounds (that an immature sand bed is incapable of processing into to nitrogen gas) to be released back into the water column. With all this in mind, cyano should be easily outcompeted for limited resources in a well-diversified system.
Biological competition in a well established DSB system will control most of the cyano problems listed above, as well as the removal of cyanobacteria itself, as there are many organisms that live in a diverse sandbed infauna system that consume cyanobacter spp. as part of their diet. Rob Toonen and Ron Shimek (heh, Mr. IO) both have recent articles about this subject, as well as Sam Gamble's articles on live sand beds. Peter Wilkens spoke on the subject at MACNA 2000, and suggests that one way of solving cyano problems is to find someone who's tanks do NOT have cyano problems, and get some of their sand to introduce cyano-consumers to problematic systems.
As far as ornamental fish consumers of cyanobacter spp., try the stripped Bristle-toothed tang (
Ctenochaetus striatus, see pp 734-35 in Baensch Marine Atlas). Under the feeding aspects, Baensch lists "...
C. striatus sucks the thin covering of diatoms AND poisonous blue-green algae (cyanobacteria) from the bottom, making it one of the few herbivorous spp. that can be poisonous (ciguatera)..." . As the fish keeping is not my forte, I will leave any suggestions for other cyano-consumers to some of the better versed icthio-types here. Keep in mind that problems with cyanobacter blooms are usually multifaceted, and having the cyano consumed by a top-of-the-chain organism generally does not remove the root causes of the bloom from the microcosm, but rather , recycles it back into the water column (although some of the nitrogen is captured as fish biomass). You need to consider putting in place some method of export of the nutrients and a limit to the import of them to deal with the problem more thoroughly.
Here are a few links to threads about cyano on TRT:
Cyanobacteria Link No. 1
Cyanobacteria Link No. 2
Cyanobacteria Link No. 3
Cyanobacteria Link No. 4
Cyanobacteria Link No. 5
HTH
