Algae is normal in aquariums, but when it takes over it usually means the balance between light and nutrients is off. Many people reach for chemical algae killers, but that often treats the symptom and creates new instability. In guppy tanks, the goal should be stable, clean water and predictable light. When you fix the cause, algae usually becomes manageable again.
Why algae spikes
- Too much light: long photoperiods or direct sunlight.
- Too many nutrients: overfeeding and rising nitrates.
- Low plant competition: algae wins when nothing else uses nutrients.
- Inconsistent maintenance: long gaps then big cleans can destabilise.
What algae is telling you
Algae is basically feedback. It often tells you that your tank has more energy (light) and nutrients than your system is exporting. The fix is to bring those back into balance.
Fixing algae without chemicals
- Reduce light: shorten photoperiod and block direct sun.
- Feed cleaner: smaller meals, less waste.
- Remove manually: scrape glass, trim affected leaves.
- Maintain steadily: regular water changes and filter flow checks.
Algae control is not a one-time action. It’s a routine. Once your light and nutrient balance is stable, guppy tanks usually look cleaner and fish health improves too.
