What size aquarium filter do I need?

As a baseline, choose a filter rated for at least 4–6× your tank volume per hour for fish-only tanks, and 8–10× for heavily stocked or planted tanks. For a 55-gallon tank, that means a filter rated at 220–330 GPH minimum. Canister filters almost always outperform HOB filters for tanks above 30 gallons. See our canister filter guide for specific model recommendations by tank size.

Do I need CO2 for a planted tank?

Not always. Low-light plants like Java fern, anubias, mosses, and most crypts thrive without CO2 injection under moderate lighting. CO2 becomes essential when you want to grow demanding carpeting plants (HC Cuba, dwarf hairgrass), stem plants at speed, or when running high-intensity lighting. Without CO2 under bright light, you create the ideal conditions for algae outbreaks rather than plant growth.

What is the best aquarium heater for a 55-gallon tank?

For a 55-gallon tank, we recommend a 200–250 watt heater. The Eheim Jager 200W is our top pick for accuracy and reliability. For added safety in larger tanks, consider running two smaller heaters (e.g., two 100W units) so that a single heater failure does not result in a lethal temperature drop or spike.

How often should I do water changes?

For most freshwater community tanks, a 25–30% water change weekly is the standard recommendation. Heavily stocked tanks may need 2× weekly. The key is consistency — irregular large changes cause more stress than smaller frequent ones. Saltwater tanks typically require 10–20% weekly changes, with more frequent top-offs to compensate for evaporation.

Aquarium Guides – Honest Equipment Reviews for Freshwater & Reef Tanks 2026

Aquarium Guides

Expert aquarium guides and equipment reviews. Compare the best fish tanks, filters, heaters, lights, and aquatic plants for freshwater and saltwater setups.