or you could just make sure that your reservoir is the correct temperature (68-72), the ph is correct, and give it a few days like you did before and it will go away.

Also, if you are using an airstone, be sure you clean all the shit out of it during EVERY reservoir change (this might help, I had to ditch my airstone and just use a small pump to keep the water circulating but the foam thing hasn't happened since).