spanko
Active Member
An Interesting read from WaterKeeper on another site.
Reefkeeping 101 -
Bogus Information
As a master of bogus information I see many threads where old wives' tales are still presented as valid answers to posted questions. Much of this mis-information has been touched on in previous columns. I’ll highlight some of the most common this month.
Water Changes Prolong the Cycle
________________________________________
This myth is so widespread that even experienced reefers believe it. People that hold to this concept seem to believe water changes remove beneficial bacteria swimming in the water column, and thereby water changes remove the bacteria you want.
While it is true that some bacteria are carried about in the water column, for the most part, bacteria do not swim in the water. If we could count them we would have several million floating around in a small tank. However, bacteria carried in the water are only a tiny portion of the overall bacterial population of a tank. The bulk of the bacteria in any tank are sessile, meaning they are attached to solid objects in the tank. A single grain of sand may have a million bacteria growing on it but those lost to water changes are very small compared to the total numbers in the biological film.
In a new tank, we are adding live rock and possibly live sand that has this biological film covering it when it is received. It is all the population that the tank will need. If the rock is curing there is an abundance of dead and dying organisms on the rock. Most of the die-off consists of sponges and other organisms that didn’t survive the trip to your tank. As the rock cures beneficial ammonifying bacteria feed on the nitrogen released by decaying organic matter and multiply at astonishing rates. A single bacterial cell may become 64 in less than a single day. Since the bacteria that turn protein into ammonia reproduce faster than those that consume the ammonia and change it to nitrate, ammonia levels climb. Ammonia levels reach toxic levels in fairly short order and surviving higher organisms on the live rock die.
This is a time to for large, frequent water changes. The water change helps remove ammonia, and other decay products from the tank, and helps the tank achieve equilibrium in which ammonia can be processed to nitrate almost as soon as it forms. It lowers the numbers of organisms that will be lost on the rock as it cures. Sure, the water changes also remove some small number of beneficial bacteria from the tank but there are far more attached organisms on the live rock and sand than are needed in the first place. The lost bacteria have no bearing on the time cycle will take and the following algae outbreaks will be shorter in duration as their will be fewer nutrients in the water column to help fuel the algae growth.
Do yourself and your new live rock a favor and do at least 25% water changes every day on a cycling tank. Even larger water changes are perfectly fine and probably will shorten, not lengthen, the cycle period.
Carrying a Slightly Lower Salinity in the Tank Lessens Disease
________________________________________
This bogus information seems to be perpetuated by the pet shop trade. The exact source of the myth is unknown, but it seems to have started in the early 1980s. I have been told it may have originated in an article by Herbert Axelrod, but cannot confirm. No matter, the concept that keeping a marine aquarium at lowered salinity, with specific gravity of ~1.019, is commonly cited as helping to prevent disease outbreaks in saltwater fish.
This idea has never been proven to help fish in any way. A specific gravity of 1.019 is far short of the level of 1.009 needed to combat ich during hyposalinity treatment. The practice may save some money for the fish supplier in it requires less salt, but it does not prevent disease. Although it doesn’t seem to hurt fish, lowered specific gravity is not good for corals and other invertebrates. They need to be maintained in the range of 1.025-1.026 for long-term health and well being. The widespread use of low salinity husbandry is why one needs to carefully acclimate new fish. If the fish is maintained at low salinity at the fish store, a sudden change in salinity can be damaging to the fish.
Reefkeeping 101 -
Bogus Information
As a master of bogus information I see many threads where old wives' tales are still presented as valid answers to posted questions. Much of this mis-information has been touched on in previous columns. I’ll highlight some of the most common this month.
Water Changes Prolong the Cycle
________________________________________
This myth is so widespread that even experienced reefers believe it. People that hold to this concept seem to believe water changes remove beneficial bacteria swimming in the water column, and thereby water changes remove the bacteria you want.
While it is true that some bacteria are carried about in the water column, for the most part, bacteria do not swim in the water. If we could count them we would have several million floating around in a small tank. However, bacteria carried in the water are only a tiny portion of the overall bacterial population of a tank. The bulk of the bacteria in any tank are sessile, meaning they are attached to solid objects in the tank. A single grain of sand may have a million bacteria growing on it but those lost to water changes are very small compared to the total numbers in the biological film.
In a new tank, we are adding live rock and possibly live sand that has this biological film covering it when it is received. It is all the population that the tank will need. If the rock is curing there is an abundance of dead and dying organisms on the rock. Most of the die-off consists of sponges and other organisms that didn’t survive the trip to your tank. As the rock cures beneficial ammonifying bacteria feed on the nitrogen released by decaying organic matter and multiply at astonishing rates. A single bacterial cell may become 64 in less than a single day. Since the bacteria that turn protein into ammonia reproduce faster than those that consume the ammonia and change it to nitrate, ammonia levels climb. Ammonia levels reach toxic levels in fairly short order and surviving higher organisms on the live rock die.
This is a time to for large, frequent water changes. The water change helps remove ammonia, and other decay products from the tank, and helps the tank achieve equilibrium in which ammonia can be processed to nitrate almost as soon as it forms. It lowers the numbers of organisms that will be lost on the rock as it cures. Sure, the water changes also remove some small number of beneficial bacteria from the tank but there are far more attached organisms on the live rock and sand than are needed in the first place. The lost bacteria have no bearing on the time cycle will take and the following algae outbreaks will be shorter in duration as their will be fewer nutrients in the water column to help fuel the algae growth.
Do yourself and your new live rock a favor and do at least 25% water changes every day on a cycling tank. Even larger water changes are perfectly fine and probably will shorten, not lengthen, the cycle period.
Carrying a Slightly Lower Salinity in the Tank Lessens Disease
________________________________________
This bogus information seems to be perpetuated by the pet shop trade. The exact source of the myth is unknown, but it seems to have started in the early 1980s. I have been told it may have originated in an article by Herbert Axelrod, but cannot confirm. No matter, the concept that keeping a marine aquarium at lowered salinity, with specific gravity of ~1.019, is commonly cited as helping to prevent disease outbreaks in saltwater fish.
This idea has never been proven to help fish in any way. A specific gravity of 1.019 is far short of the level of 1.009 needed to combat ich during hyposalinity treatment. The practice may save some money for the fish supplier in it requires less salt, but it does not prevent disease. Although it doesn’t seem to hurt fish, lowered specific gravity is not good for corals and other invertebrates. They need to be maintained in the range of 1.025-1.026 for long-term health and well being. The widespread use of low salinity husbandry is why one needs to carefully acclimate new fish. If the fish is maintained at low salinity at the fish store, a sudden change in salinity can be damaging to the fish.
