As the weather finally warms up in May, everything in your pond starts moving faster. Your koi are more active, your plants are putting out new shoots, and unfortunately, the “bad” algae is usually looking for a foothold. While we all love seeing that activity, there’s a hidden biological shift happening underwater: as the water temperature rises, its ability to hold onto dissolved oxygen actually drops.
Think of it as a crowded room. In the winter, it’s like the windows are wide open—the water is cold and packed with oxygen. By May, it’s like those windows are closing, but everyone inside is starting to exercise. Your fish need more oxygen to fuel their higher metabolism, but the water is offering less of it.
The Biological Oxygen Factory
Most pond owners immediately think of air stones or waterfalls when they hear “oxygen.” Those are great for moving water, but there’s a much more efficient way to oxygenate a pond: Diatoms.
When you provide the right nutrients to encourage diatom growth, you’re essentially turning your pond floor and walls into a massive oxygen factory. Through photosynthesis, these tiny “good” algae release pure oxygen directly into the water column. Unlike a bubble from an aerator that mostly escapes into the air at the surface, the oxygen produced by diatoms is already dissolved and ready for your fish to use.
By focusing on diatoms in May, you aren’t just clearing up the water; you’re making it easier for your koi to breathe during the first real heat waves of the season. It’s about working with the biology of the pond rather than trying to force it with more electricity and louder pumps.
FAQ: Oxygen and Your Pond
1. How can I tell if my pond is low on oxygen?
The most obvious sign is “piping.” If you see your fish hanging out at the surface or congregating near waterfalls and looking like they are gasping for air, your oxygen levels are likely dangerously low. You might also notice your fish becoming lethargic or refusing to eat.
Not necessarily. Mechanical aeration is a great backup and helps with gas exchange at the surface. However, Nualgi acts as a biological supplement by boosting the natural oxygen production of diatoms. Think of the air pump as the “lungs” and the diatoms as the “blood supply” that keeps everything moving efficiently.
3. Why does oxygen drop so much at night?
Plants and algae produce oxygen during the day through photosynthesis, but at night, the process reverses—they actually start consuming oxygen. This is why most “oxygen crashes” happen in the early morning hours right before the sun comes up. Having a healthy population of diatoms helps ensure the water is fully saturated before the sun goes down.
4. Does warm water really hold less oxygen?
Yes, it’s a physical law of water chemistry. The warmer the water, the less “room” there is for oxygen molecules to stay dissolved. This is why May and June are such critical months; the temperature is rising, but the pond’s inhabitants are at their peak activity levels.
5. Can I have too much oxygen in my pond?
In a typical backyard pond, it is almost impossible to have “too much” oxygen through natural means. Your fish will simply take what they need. High oxygen levels also help beneficial bacteria break down muck and fish waste more quickly, which keeps your water clearer in the long run.
