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Ph 8.25, Nitrate, Nitrite, Ammonia all below detection (salifert) Calcium 500, Alk 11. I add only Kent Kalkwasser and Seachem Reefbuilder for buffering. I feed Formula one with selcon added three timer per week. I dose DT's every other day. I have tried everything and am frustrated. I have heard that R/O will not remove silicates
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Your numbers look ok and the things you are doing should be ok also. Keep in mind that although your nitrate may be undetectable, as well as phosphate and other nutrient problems, that cyano will uptake these nutrients and make them unavailable to other organisms, as well eliminating the ability to detect them in the water column if your numbers are moderate to low to start with. Cyano grows extremely quickly: it can double its population in 30 minutes. If there are no other means of controlling the population in the tank (consumers or competitors for the same nutrients), then it can quickly overtake any competition and bloom in a single day. Often the blooms will follow the photoperiod, and much of the bloom will die each night. As it dies, it releases it's nutrients back into the water column, making those resources available for the next bloom unless they are removed. More than likely, your bloom is almost non existant in the mornings. This is when your water parameters should be tested. You may find that the pH is low also, this is normal, but higher pH levels of 8.3 to 8.4 in the morning help to eliminate cyano blooms. The blooms will get larger over a period of time, but daily cycles of growth are the usual for these organisms. One of the best methods of removing the nutrients and the seeding organisms is to wait until the end of a day's growth and siphon out the mats. this not only removes the slime, but removes the nutrients locked up in ther cells as well. Doing this over several days will probably stop the blooms. Drip a little extra kalkwasser into the system to additionally boost your dKH and calcium, as well as remove some of the phosphate. If you have a buddy nearby that has a similar setup but doesn't have cyano problems, ask them for a cup of their substrate. Peter Wilkins addressed this issue at MACNA this year, and thinks that predation of the cyanobacteria by a cyano-consumer is the best way to eliminate the blooms.
The physical factors that Doug and Dick have addressed are all part of the picture, especially circulation. Cyanobacteria has very poor active transport and must absorb a good deal of its nutrients via diffusion, and needs slow or still wawter to do this to its best advantage. The real kicker is that if the water is still enough, cyanobacteria has the capability to fix nitrogen from the atmosphere instead of relying on nitrate or ammonia for its nitrogen: cyanobacteria are members of the bluegreen algae, probably some of the first creatures to evolve out of the primordial soup. They are the reason that earth has an atmosphere with 20% oxygen as well as a fairly low carbon dioxide content. Many bentic organisms use cyanobacteria as a food source, so using one of the antibacterial products is like asking your sandbed to start the maturation process all over again. I would encourage you to hang tough and to do the things that BIOLOGICALLY control the bloom, as it will ultimately lead to a more stable sand bed, and thusly lead to a more stable microcosm in your little slice of the ocean.
Hope this helps, as Doug said, there should be more info in some of the older threads. BTW, silicate in the form of organosilicates will feed
DIATOM blooms, but really don't affect cyanobacteria. However, phosphates DO feed cyano blooms, all the more reason for using RO/DI water.
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[ 03-20-2001: Message edited by: tdwyatt ]
