Thank you for waiting. I appreciate your patience. While it's not possible to be certain based only on an online description, it seems likely that Leah is suffering from a respiratory infection. Whenever a turtle makes noises, we suspect that. The noise often originates in the lungs. Opening the mouth wide is an attempt to get more oxygen into the lungs. The floating and difficulty staying above water are signs there may be fluid in the lungs - pneumonia. I know you would like a home treatment, and I would like to give you one, but unfortunately, this is a situation where there isn't one. A safe prescription antibiotic, such as Baytril, will probably be needed.
Make sure you have proper temperatures in the tank, as being too chilly can make this condition worse. Warmth gives the immune system a boost. The area under the basking light should be 85*F to 90*F. The water should be 78*F to 82*F.
While it doesn't have something to do with Leah's illness, if you don't have a UVB light, all of your turtles will develop Metabolic Bone Disease. I am sedning along a care sheet I've written for slider turtles. You can use it as a checklist to make sure everything is just right. Pet stores often give out incorrect information, so it's best not to rely on them.
This link will take you to a directory of reptile vets:
If you have more questions, just let me know. I hope you'll be able to find help for Leah, and she will reach a full recovery.
My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back, I am happy to address follow-up questions. Please remember to rate my service after you have all the information you need. I will greatly appreciate a positive rating as that is the only way I am compensated. Thank you!
SLIDER TURTLE CARE SHEET
Well-cared for sliders can live 30 years or more.
It's recommended that a baby slider have at least a 15 gallon tank. By the time the turtle is 3-4 years old, it will need a 60 gallon tank, so it's best to get the biggest you can in the beginning. You can also use a large RubberMaid tote. That's not as pretty as a tank, but costs a lot less. Set up the tank so there's a land area and a water area. Put the basking light at one end so the whole tank doesn’t get too hot. You want the water to be about twice as deep as the turtle is long. If the turtle is two inches long, you'll want four inches of water.
Temperatures and Basking Area
Turtles need certain types of lighting and need to be warm. Air and water that are not warm enough can lead to fungal and respiratory infections and unhealthy shells. Turtles must have a basking area where they can get out of the water, dry off, and bask in very warm light. The ambient air temperature in the tank should be around 75 *F (24*C) , with the basking area warmer still. Over the basking area there should be some sort of lamp that will take a 40-60 watt incandescent bulb (or you can buy a ceramic light fixture made just for reptiles). If you live in an area that has farm stores, you can buy a metal light fixture made to keep baby chicks warm for just a few dollars. Don't buy the accompanying bulb, however. You need an ordinary incandescent bulb in the basking light. Hardware stores sell similar fixtures as work lights. The basking area should be kept at 85-90*F (29 to 32*C). Use a digital probe thermometer to be sure. You can adjust the temperature by raising or lowering the light fixture.The lights that come with the covers on aquariums are not suitable for turtles. You'll also need a submersible aquarium heater that will keep the water 78-82*F (26 to 28*C).
It's extremely important that you buy an additional light that produces UVB rays. A Reptisun 10.0 is a good brand that does. If you choose another brand be absolutely certain it provides UVB rays. Don't take the word of pet store personnel, but read it for yourself. Full-spectrum, DayGlo, SunGlo, UV, or UVA are not the same thing. I'm putting a lot of emphasis on this because it's crucial to your turtle's health. Without this light, Metabolic Bone Disease (MBD) will develop because your turtle won't be able to produce vitamin D. Vitamin supplements are not a good replacement for the proper lighting. MBD causes a very slow and painful death.UVB bulbs must be replaced every six months as they lose their effectiveness after that, even though they may still look fine. Light that comes through a window isn't sufficient because the glass filters out most of the rays turtles need to stay healthy. To prevent MBD, turtles also need calcium. The easiest way to provide it is to place a cuttlebone in the tank. Cuttlebones are sold in bird departments of pet stores.
Turtles are very sensitive to water quality. Even if you change the water every day, it can still contain harmful chemicals. A good filtration system is essential. Water changes are also needed even with a filter. If the tank is too small, no filter can keep up with the amount of waste that turtles produce.
Feeding is an area where pet stores often give out bad information. Commercial food should make up only 1/4 of the diet. Animal products (cooked meat, earthworms, canned cat food) should make up another 1/4. The remaining half should be plant foods (dark lettuce like romaine, bits of strawberry or melon, etc.). Hatchlings should be fed every day. Older turtles should be fed 3 times per week. Overfeeding can lead to gout and kidney failure.
For Further Reading
This is among the most reputable sites on turtles.