Although API makes great canister filters and water test kits, I'd leave water quality fixing and bacterial supplementation to
Seachem. Their dechlorination product,
Prime, works instantly. As soon as you put it in the water (2 drops per U.S. Gallon) you can add the water to the tank. This product also replaces and/or rebuilds the slime coat of fish and invertebrates.
Plus they have a product for everything, a water clarifier, supplemental bacteria, filter media (Carbon, porous materials for bacterial growth, etc.), plant food, fish food, coral food, gravel, sand, gravel/sand that helps plants grow, some of the best medication available, brackish salt, marine salt, pH buffers, and test kits.