If lot of uneaten food is sitting in the filter material, that may be making the problem worse. Be sure to rinse your filter material in tank water that you will then discard (Keep the filter material -- it has most of your beneficial bacteria). Same with uneaten food sitting in the bottom. Do a good vac job. Ammonia at .25 ppm is reason to evaluate, but not reason to panic. If it gets over that it is best handled with a large immediate partial water change (or several if needed). Most water conditioners like Prime when used in the normal recommended amount during PWCs will help temporarily and give your biological filter a chance to catch up, but it is no substitute for the PWC..
BTW, don't kill the mrs., but do teach her the proper amount to feed and explain about the ammonia and the other dangers to the fish of overfeeding. I'd certainly explain to her the difference between nature and our little closed systems in our tanks. My mr. leaves our tank completely to me so I don't have to deal with that issue, lol.