Gloss will be better if you get water and salt on it. It will all look the same fropm inside the tank though no matter what finish it is, semi, flat or gloss. As for paint I like latex applied with a small 3" cheap foam roller. I buy the cheapest latex paint I can find at big box or wally world. I have used lac, acrylic enamels, latex and they all work. All are easy to remove with a razor blade if the occasion ever arises. Spray paint will take considerably more coats but if you use Krylon or spray lacquar it will dry pretty quick so more coats can be applied in a shorter interval. Krylon is fairly fast dry as well, and latex dries fairly fast especially if a fan is applied to it.
