Dennerle CO2 Quick Test
Not sure if your plants are getting enough CO2? The Dennerle CO2 Quick Test gives you a definitive answer in seconds. Just fill the test tube with aquarium water, shake it briefly, and the color tells you everything you need to know.
What Makes This Product Special
Most aquarium water tests require mixing reagents, waiting several minutes, and comparing subtle color differences. The CO2 Quick Test skips all that. Its five-color comparison scale is immediate, clear, and intuitive — no chemistry knowledge needed, no ambiguity in reading the result.
Key Benefits
- Results in seconds — the fastest CO2 test for home aquariums
- Clear 5-color scale: blue (too little) → green (ideal) → yellow (too much)
- No KH measurement needed — no conversion tables or calculations
- Pack of 2 — test at different times of day for a full picture
- From Dennerle — a German aquarium brand trusted by aquarists since 1966
- Freshwater only — designed for planted tanks with CO2 injection
How to Use
Fill the test tube with aquarium water up to the marked line. Shake briefly. Compare the resulting color to the five-color reference scale immediately. Green = perfect. Blue = add more CO2. Yellow = reduce CO2.
Pro Tip on Timing: Test mid-day, halfway through your light period. CO2 levels are naturally lowest in the morning (before plants start consuming it in earnest) and highest in the afternoon. Testing mid-day gives you the most representative reading.
Who Is It For
Anyone with a planted freshwater aquarium and a CO2 injection system. Beginners setting up CO2 for the first time, and experienced aquascapers who want a quick sanity-check without unpacking a full test kit.
Technical Specifications
- Contents: 2 quick CO2 tests
- Method: colorimetric, 5-color scale
- Result time: a few seconds
- Water type: freshwater only
- Does not measure liquid carbon fertilizers
Compatibility
Works alongside all pressurized CO2 systems, CO2 bio-reactors, and CO2 tablet systems. For continuous 24/7 monitoring, pair it with the Dennerle CO2 Langzeittest Correct permanent drop checker.
Expert Tip
Use this test whenever you adjust your CO2 bubble rate, after a water change, or any time your plants look stressed or algae suddenly increases. A 10-second test can save hours of troubleshooting.
