Re: Fishing with a 7wt 7 1/2 rod just bought
You can catch trout with any rod + reel combination, however some rods are better suited to certain waters and types of fishing. For the scenario you describe, the 5wt rod will be a better fit.
You could use the 7wt but it may pose some challenges in terms of presentation (for a beginner caster). You may be able to get away with the 7wt for nymphing and streamer fishing but dry fly presentation will pose some challenges unless you use very long leader + tippet combinations.
I would use the 7wt solely for streamer and heavy nymph (double nymphs + shot) and use the 5wt for dry flies, smaller nymphs & dry-dropper scenarios.
Hope this helps. By the way what is the action OR make / model of the 7wt rod?