Wow, that's a pita!
Foam mats are a good save.
If there's nothing biological on it, no, it shouldn't, unless for some reason it comes with ammonia. One really good item to have at all times is a product called Prime: it can make tapwater safe to use---doesn't knock out ALL the unwanted chemicals in tapwater that can throw your water balance off, but will remove those that are a hazard to life and fishes.
A second one is Polyfilter. These resin-impregnated pads will suck up things like metals and other contaminants (say your niece dropped your tv remote into the tank and you didn't find it for hours) and get them out of your water. Also the color it turns tells you what it sucked up.
If the foam gets clogged, some blue/white mesh filter from your local pet store should be fine enough to serve as a prefilter for your foam.
Best of luck---sorry we were slow getting to your question. We're usually faster.