Summer Care for Aquatic Plants: Preventing Melt & Algae in High Water Temperatures

Summer is a battle against rising water temperatures for planted aquariums. Many aquatic plants start declining above 28 degrees Celsius, and some species melt away entirely above 30 degrees. Learn the proper countermeasures to get through summer.

Effects of High Water Temperature on Aquatic Plants

Rising water temperatures cause various negative effects on aquatic plants.

• Melting: Delicate stem plants like Rotala and Pearl Grass may develop transparent stems and melt away at high temperatures
• Growth slowdown: Most aquatic plants thrive at 22-26 degrees Celsius; photosynthesis efficiency drops above that range
• Algae proliferation: High temperatures accelerate blue-green algae and filamentous algae growth
• Decreased oxygen: Higher water temperatures reduce dissolved oxygen levels, increasing root rot risk

Choosing Aquarium Chillers and Cooling Fans

Cooling equipment falls into two main categories: chillers and fans.

Aquarium Chillers - The most reliable method for stable temperature reduction - Peltier-type units are suited for small tanks (60 cm and under) and are affordable but have limited cooling capacity - Compressor-type units cool powerfully even for large tanks, but are bulky and require attention to heat exhaust - Setting the target temperature around 25 degrees Celsius provides automatic management

Cooling Fans - Direct airflow across the water surface for evaporative cooling of 2-3 degrees Celsius - More affordable and easier to install than chillers - Effectiveness decreases on humid days, so combination with air conditioning is recommended - Increased evaporation requires frequent top-offs

If budget is a concern, start with a fan and consider adding a chiller if temperatures still exceed 28 degrees Celsius.

Shading and Lighting Adjustments

Longer summer daylight hours require attention to lighting management.

• Block direct sunlight: Use shade curtains or bamboo screens for window-side tanks
• Reduce lighting hours: Cut from the normal 8 hours to 6 hours to suppress algae
• Shift lighting schedule: Avoid high-temperature daytime hours and run lights at night
• Reduce LED output: If your light has dimming capability, reduce to 70-80% in summer

Shading risks slowing plant growth, so adjust while monitoring algae conditions.

CO2 and Fertilizer Adjustments

CO2 and fertilizer management balance needs reassessment during high-temperature periods.

CO2 Management Tips: - CO2 solubility decreases as water temperature rises, creating temptation to increase dosing, but balance with oxygen depletion risk is crucial - Strengthen nighttime aeration to maintain oxygen levels - Monitor concentration with a drop checker while making fine adjustments

Fertilizer Adjustment Tips: - Reduced plant growth in summer also means reduced nutrient consumption - Reduce liquid fertilizer to half or 70% of normal amounts to prevent feeding algae - Hold off on adding substrate fertilizer (solid fertilizer) and observe with existing amounts - Potassium has relatively little impact on algae, so continue normal dosing based on plant condition

Summer Algae Control

High temperatures create favorable conditions for algae, making preventive measures essential.

• Increase water change frequency: Go from weekly to twice weekly to prevent excess nutrients
• Add algae-eating crew: Supplement with Amano shrimp and Otocinclus
• Room temperature management via AC: Controlling overall room temperature fundamentally suppresses water temperature rise
• Clean the filter: Bacterial activity changes at high temperatures can reduce filtration capacity

Find Aquatic Plants on BuriChoku

If you want to introduce heat-tolerant aquatic plants, search BuriChoku for aquatic plant breeders. The ability to directly ask breeders "Which varieties handle high temperatures well?" is a major advantage. Purchase healthy aquatic plants directly to keep your summer tank beautiful.