having worked in the insurance industry for a number of years here is my experience with farmers. If they can they will deny a claim. they did that once when i was hit by one of there clients they claimed it was a 50/50 accident. depending on your policy if it is a typical homeowners policy, meaning you own the home, it's not a rental or a condo. then you can claim water damage that is no different then if your toilet exploded, or your water pipe burst in the wall. they would repair the damaged furniture and whatever part of the house is damaged. however, the policy will not cover pets of any kind, so getting them to replace a tank that cracked would be tricky since to them it's where your pets live. I would call them back and resubmit the claim as just water damage. and when they finally get to how it happened you can let them know you have a tank that cracked but never try to recover any lost animals or maybe even hardwhere. the most important thing is to get your house repaired.
hope this helps.
Chris