ZooMed AquaCool Aquarium Cooling Fan Style:Cooling A sensor changes color reversibly

A sensor changes color reversibly from yellow to orange to red alerting you to shifts in pH levels between 5

Check out the AquaSun Aquarium Timer

Red Sea’s Nitrate Pro Reef Test Kit is an advanced colorimetric test with comparator

Response to decreasing ammonia is slower

ZooMed AquaCool Aquarium Cooling Fan Style:Cooling A sensor changes color reversiblyFully adjustable side mounting Aquarium Cooling Fan. Low voltage (12 v) for maximum safety when used near a wet environment. Better than overhead fans: Side mounted fan assembly to minimize water splash on the motor and to prevent accidental immersion. Multi directional discharge nozzle for precise air flow focus. Fully adjustable, wide discharge nozzle for maximum cooling due to increased air water contact.