Hi Cassie and welcome to TFF!
Ok, so it looks as if you have jumped right in with both feet. To address your question, it sounds like a bacterial bloom. Ok, I'll try to not get too technical. When you add water conditioner to your tank, it removes chlorine. This makes the water safe for life, and there are a group of bacteria that eat the organic material in that water. Once the organic material is gone, the water will clear.
Cassie, I think petsmart has given you some bad information. Setting the tank up and letting it run for 24 hours is a good practice for checking the seals on the tank and to let you see if your filter is working properly, but it does nothing to make the aquarium safe for fish to live in. Fish produce ammonia, and that ammonia is toxic to them. Imagine swimming, living, and eating in your toilet. It's just not healthy. Luckily for us, there is a species of bacteria that eat ammonia and change it into a compound called nitrite. Nitrite is also toxic to fish. Again, there is a species of bacteria that eat nitrite and turn it into a compound called nitrate. Notice the spelling difference between nitrite and nitrate. Now nitrate is pretty harmless to fish, and we remove nitrate when we do partial waterchanges. This process is called The Nitrogen Cycle.
There are 2 ways to make your tank safe for fish. One is called a fishless cycle and the other a fish-in cycle. A fishless cycle involves using household ammonia to grow the proper species of bacteria before you add fish. This method is the least amount of work and it is better and healthier for your fish.
The second method, fish-in cycling, involves adding a few hardy fish to the tank to provide the ammonia that's needed to cycle your tank. Unfortunately fish cannot take much, as little as .25ppm, can cause permanent gill damage. If the level goes higher than .25, you would need to remove the water, and replace it with new temperature matched conditioned water. Sometimes it takes 2 to 3 75% waterchanges
everyday to control the ammonia. It's a lot of work, and very hard on your fishy friends.
Take a look in our
Beginners Resource Center. There's loads of information that you will find handy.
