Rusty Tank

Question
I have had my 55 gallon tank set up for about a 1-1/2 months now.  We recently moved long distance so it is not the first time this tank has been set up.  My tank was doing wonderfully and the fish were thriving. I fed my fish in the morning and everything was fine, when I got home from work I had lost 6 fish (guppies and tetras), and I had a slight tinge of rust on my plastic plants and decorations and my water seemed rusty.  The next day I lost 3 more fish (bala sharks).  I have never been big on water testing and have always had gorgeous fish and tanks.  But this is a problem I have never had before.  I've changed my filter and done a 25% water change but it has done no good.  

I currently have in my tank 3 angels, a pleco, 1 dalmation guppie, 2 platies and 2 neons left.

I was going to take a water sample in today to the pet store to see what they say.  

PLEASE HELP!!

Answer
Hi Jewel
If you haven't gone to the pet store yet, I'd recommend buying your own test kit.  API makes a liquid dropper test kit, it's about 30.00, tests for ammonia, nitrites, nitrates, and ph.  

Now, how long has the tank been set up since you moved?
And, are these the fish you had previously, or did you buy new fish?
When you moved, did you keep the decorations, gravel/substrate, and filter media(filter pads and whatever else you had in the filter) wet?
Are you on well water or city water?

I got a feeling your tank is going through a cycle process, especially with so many dying off.  But let me know what the water test readings are.  You really should do it yourself, most pet stores will use the dip stick test kits, and they're not as accurate as the liquid kits.  And, I don't know what store you're going to, but a lot of them will give bad information.  They'll say a small amount of ammonia or nitrites is safe, but that's not the case.

Get back to me when you can, and we'll take it from there.

Christy