I agree, there's no way that Hank is not doing anything with this information. The only issue is whether or not he can keep his cool until he has some hard evidence, now that he knows Walt is behind everything.
Also, what a fucking troll near the end with Walt Jr./Holly near the pool, and with the sunscreen and everything, I was sitting there for a good 2 minutes waiting for something bad to happen... then Hank goes to take a shit with 30 seconds left into the episode lol. Nice cliffhanger though. Sucks we have to wait so long. Assholes.