Posted: Sun Mar 25, 2007 1:03 pm
It sounds like a bacterial bloom. How long have you had the tank up and running? Usually when first setting up an aquarium with turtles or fish, it will go through a cycle like this while the natural bacteria that break down the turtles waste begins to grow. Ideally, the bacteria need a lot of surface to colonize on and you want them to do this so they will help keep the water from getting toxic from the waste. Any surface in the aquarium, glass, decorations, plastic plants, etc. will provide the bacteria a place to grow. Also the media in the filter is meant to provide the most surface area for bacteria.
When doing water changes and cleaning the tank and filter, you want to keep in mind that you need the bacteria that is covering everything. So, don't use any detergents, don't scrub, and don't replace everything at once. For example, when doing a water change, only change 50% or less each time (unless it's an emergency). Then take the filter media and gently rinse it in the old tank water and then put it back in the filter. Replace only one part of the filter at a time: one month replace the carbon but leave the sponge, the next month replace the sponge but leave the carbon. That way, there is always a healthy colony of bacteria present to keep the water clean.
If your tank is relatively new, you will need to be patient while the bacteria cycles. When first adding the turtles, the ammonia levels will rise. This is toxic to fish and turtles, but the bacteria will start to bloom to consume the high amount of it. In doing so, they convert the ammonia to nitrite (also toxic but not as bad as ammonia). Once the population of this first type of bacteria has grown enough to keep up with all the ammonia, the levels of nitrite will start to increase. Now a second type of bacteria that feeds on nitrite will start to grow (a second bloom). They in turn will convert the nitrite to nitrate which is a much less harmful substance and is tolerated by fish and turtles to a much higher degree. Keeping the nitrate level low is best done by partial water changes (10% each week or 20% every other week or 40% once a month, it's up to you and how much you feed your turtles and how many animals you have in the aquarium).
The cloudiness you see is usually because there's more ammonia in the water than the bacteria that have colonized the surfaces in the filter and tank surfaces can keep up with. Therefore, more bacteria continue to grow but since the surface areas are already colonized they remain in the water making it cloudy. As the ammonia is consumed, the excess bacteria die off until only enough remain to just keep up with the waste load of the inhabitants. A second bloom may also occur with the nitrites, but it should all eventually go away.
If you clean the filter too thoroughly during this process, it will have to start all over again. Also, if you change too much water during this process, there may not be enough ammonia or nitrite left to spark the bacteria to grow. Some say that these bacteria don't start to grow until the ammonia (or nitrite) reaches a certain peak level.
Be patient and let the tank cycle. This is the time most new aquarists have difficulty getting through with fish. Turtles seem to tolerate the high levels much better than fish though.
