Goldfish tank

Question
I bought my daughter a 10-gallen tank with a filter for two very sweet goldfish she picked out from Animart (our local pet store). I am doing my best to keep it clean, but the water never appears clear. We have had the tank for a month now. I syphon it weekly and replace the charcoal bag in the filter weekly as well. I noticed what appeared to be a rust-colored substance growing on the rocks and fake plants we had in the aquarium, so I took those out and washed them with vinegar. That same rust-colored substance is on the inside wall of the aquarium and I'm not sure how to clean it off. We bought seven snails to help keep the tank clean and they seemed to be diligent workers for the first 4 days but have done nothing but hide in the rocks at the bottom of the tank since then. The water still continues to look milky, though that phases in and out. I want to keep these fish alive for my daughter and want to make sure I'm doing everything correctly. Please help. Also, we currently feed them twice a day.

Answer
Lindsey,

 When you bought the tank, did you cycle it for 2 weeks before you put the fish in? What kind of snails did you buy? Goldfish are very good at eating snails, so it wouldn't surprise me if the reason they are hiding is because the goldfish are trying to eat them.. Also, goldfish need a lot a room. For your 2 goldfish, you need at least a 30 gallon tank. They can grow to 6" long even more in one year. As for the rust colored stuff growing in your tank, it is called diatom algae. It is part of your tank set up or cycle. This should clear up in a week or two. I would suggest getting a bristlenose pleco but your tank is over crowded as it is. As far as the charcoal, I would replace it once a month. When its time to change it, just open the bag and add more in. This will save money on replacing the whole filter. I hope this helps.