There’s green fuzz on your glass. Green fuzz are crawling around your planted tank. How did this happen?
Where did it come from? One day your plant appear vibrant and lush, and then the next they resemble moss balls growing under water. The first thing you think of is the light.
After all, that was the most expensive part of your setup. You purchased that fancy fixture in hopes of making those plants grow, yet now it appear to be feeding something completely different. Algae and light do not have an on and off switch.
Rather, it’s a poorly tuned engine. If you don’t give it any fuel, nothing happen. If you give it too much fuel, you’re in for a mess.
Mastering Algae Control Through Proper Lighting
Understanding Algae and Light Balance
Most often, it isn’t the absolute number of photons reaching the water. It’s about the balance. What are your plant doing with all of that energy?
If they aren’t using it, the algae will. That’s the rule of the hobby. Typically, folks begin to troubleshoot with light intensity.
But the solution of making the bulb brighter doesn’t work very well in most cases. Algae is opportunists scavenger feeders. Bright light doesn’t matter.
Dimmer light doesn’t matter. What matters is whether there’s light when the plant isn’t hungry. There’s a saturation point on a plant.
This is the point where they’ve absorbed as much carbon (from the light) and nutrients as they can process. Beyond that, more light is simply wasted heat, and that wasted heat feeds the algae. Light duration and spectrum matter more then intensity.
Optimizing Light Duration
The silent killer in most new tank is duration. Twelve hour days seem normal. It’s not.
Plants are shy, especially new ones. They hasn’t had time to develop their root system and therefore aren’t making food at maximum efficiency. Long hours of light are like putting a banquet out for somebody that can only manage an appetizer.
All those leftovers just go bad. In your planted tank, the leftovers is algae. Begin with four hours.
Add thirty minutes weekly. Allow the plant to adjust to the light schedule. Ramp up gradually so the good microbes can get established before inviting the party crashers.
Choosing the Right Light Spectrum
Speaking of Spectrum, this is a bit of a surprise. There are two primary spectrums of light that plants require most: Red and Blue. That’s because green is reflected off plants making them appear green.
So when you have a fixture that’s producing mostly white or green light, you’re essentially beaming a flashlight onto your algae and depriving your plants of the light they need most. Seek out something that lets you dial in the spectrum. During their peak periods, a highly red-shifted light will drive plant into overdrive.
Blue light stimulates stem elongation and leaf growth. The spectrum is more important then the sheer wattage. But add some CO2 into the mix and things change.
The Role of CO2 Injection
Your plants will be highly efficient machines in a high-CO2 environment. They’ll process more light; they have the fuel for it. In an environment without CO2, the plants’ hands are tied; they’re limited by carbon availability.
Extra light isn’t used. It’s no wonder that high-tech tanks running CO2 injection can run bright lights without algae problems. Low-tech tank need to run shorter durations or lower lights.
The level of light provided is only as good based off the carbon source supporting it. The other side of the equation is nutrients. Starving a tank of nitrates/phosphates doesn’t help if you’re trying to cure your algae through light manipulation.
Maintaining Nutrient Levels
Food. Plants require food. They don’t grows when they’re hungry.
When they aren’t growing, they can’t absorbs light. The algae moves in to take up the slack. Test your water.
Maintain nitrates at 5-10 ppm. Keep phosphate levels high enough to be detected. Regularly feeding the plants ensures they’ll outcompete the weeds.
Synchronizing Tank Parameters
Consistency matters. Spikes & crashes lead to stress, and stress leads to algal blooms. Turning the dial down isn’t always a solution.
It’s an exercise in synchronization. Match the light to what your plant can actualy use. Then adjust the duration and brightness.
Then tune the light to the plant species. Keep nutrients and carbon levels steady. And then there’s nothing for the algae to grow on.
Water clears up again. The plants come out. Your garden begins to shine just like you paid for.
