Straight Glass Tube Rhinox CO2 Bubble Counter - Helps Maintain Safe and Healthy CO2 Levels for Plants & Fish - Includes Free Check Valve - For CO2 Diffuser, Live Aquarium Plant Aquascaping C02 System ENCOURAGES HEALTHIER AND HAPPIER AQUATIC PETS & PLANTS --- Actively reading the CO2 amount in your aquarium water is just as beneficial to your aquatic pets as it is for your plants. Accurate CO2 levels (directly linked to the important pH levels) in your fish tank encourage growth, vibrancy and alleviate any unnecessary stress on your aquatic plants and fish thus, maintaining the underwater ecosystem. QUICK AND EASY TO CONNECT TO CO2 DIFFUSER SET --- When used in conjunction with the Rhinox CO2 Diffuser Set or a similar CO2 monitoring system, the glass tube bubble counter simply connects to the existing hardware in minutes. At a practical size of 3 (7.5cm) in length with a diameter of  (0.8cm), the sleek and elegant design of the transparent tube installs without intrusion or distraction from your beautiful underwater habitat. CRAFTED WITH HIGH-QUALITY SILICATE GLASS --- Although many types of glass have some fragility, silica-based glass is high-quality, temperature-resistant and long lasting. Commonly used for windows and dishware, the glass used in the straight tube bubble counter is crystalline and transparent. This makes it extremely easy to count the bubbles and estimate your aquariums CO2 level. USE WITH RHINOX DIFFUSER KIT OR DIY SET --- Designed to fit perfectly with a Rhinox CO2 Diffuser Kit, the glass tube bubble counter also works great in many do-it-yourself setups. The straight tube glass device and red bored glass check valve set fit inline and take up very little space. The pair also work on DIY CO2 generator systems that use ingredients such as baking soda, yeast and sugar. INCLUDES A BONUS, CORRESPONDING CHECK VALVE --- The set that you receive includes two pieces: a straight tube glass device and a slightly smaller red-bored glass check valve. The supplemental CO2 check valve allows air to flow only in one direction to easily monitor the water and air flow. Bubbles are formed by the CO2, the higher quantity of bubbles indicates a higher level of CO2.