Dirty and smelly fish tank

Question
Hi Lynda, I have a biube fish tank which I love and I've never had a problem with keeping my water clean before until recently. (I have fancy guppies by the way in my tank). I just cleaned my tank and changed my filter about a week ago and it's already dirty and smelly and the filter turns red which it's never done before.  There's also slime covering my decorations and rocks which has never happened before either.  I'm not cleaning my tank any differently or using any new products.  I did recently move to a new apartment so I don't know if the water could be different or what.  Do you have any suggestions?  Thanks so much!

Answer
Hi Jennifer,
Your water could be different.  Check for ammonia, nitrates, and the PH.  You can get these small tests at the Pet Store for a small sum.  They should be number one in your fish cabinet.

 Maybe it is the location, are they getting too much sun?

If you didn't keep your old sponge, and bought all new material to put in your filter, added all new water, this also could be the reason.  
Check your water, make sure it is okay, and if it isn't, buy a used sponge from your Pet Store so that your water will get the good bacteria it needs quickly.  
When setting up an aquarium, we should always keep the same filter material, and some of the water the fish were in.  This is very important.  When you do this you keep the good bacteria that fish need to survive.
You could also call the Pet Store in your area, and ask them about the water quality.  
Hope this helps
Lynda