Holidays: the aquarium and the pond without us

It is summer and many of us are going on vacation.

But if you have an aquarium, a pond, poubellariums or micro-ponds, it is impossible not to ask the question: what will they become in our absence?

 

 

The answer to the question is very different depending on whether you are dealing with an aquarium (natural or techno), or an outdoor body of water.

 

The easiest is the pond.

If its level is sufficient before leaving, you have nothing to do. The fish will eat less, but this is the season when insects lay eggs en masse: mosquitoes, dragonflies, diving beetles, horseflies, some hoverflies, various Chaoborus, Chironomids, Ilybius, Gyrins, etc. They will manage without you to feast on incredibly varied and nutritious critters, just like in nature. A pond is a living place, but beware! The fish density is always much higher than what nature intended. So know that they will be hungry anyway, but it will not be dramatic for them.

 

However, if your pond is very small (less than 500 liters) and very crowded, consider filling the water level to the maximum before you leave and, possibly, shading the surface. In case of a heatwave, oxygen could become dangerously scarce there.

 

 

For poubellariums and micro-ponds, there is a difference. Unless they are partially or totally buried, the walls are exposed to the sun. Warming through the walls can be very significant, especially if the container is black, exposed to the sun, or if its volume is small.

During periods of intense heat, the temperature could rise dangerously fast. If part of it is buried, the bottom can stay cool (like the bottom of a pond). Otherwise, consider placing a cover on one side to keep the wall protected from direct rays. Why not use the lid usually sold with the trash bin? Fixing it vertically against the wall can be enough to make a heatwave shield...

 

 

If your body of water has no fish, it is nonetheless sensitive to heat. Each critter has its own particular sensitivity to temperature and therefore to the scarcity of oxygen. The most resistant are ostracods. I have observed some that continued to reproduce in greenhouse water at over... 55 degrees!

 

The question of water level is also vital. In summer, evaporation is much greater than precipitation. A storm of 15 to 20 mm (thus quite heavy) will only raise the water level by 1.5 to 2 cm. However, evaporation occurs continuously, day and night.

It is therefore absolutely necessary to "top up" before leaving. The risk of overflow is negligible, the risk of drying out is very serious.

 

Regarding the aquarium, the only problem is food. Less exposed to temperature variations than outdoor water points (especially in a house with closed shutters), and no risk of drying out either.

 

The dirtier your aquarium is, the more natural it is and the more your fish will find something to nibble on.

Microfauna is never completely absent. Nothing prevents you from adding a few critters before leaving. Daphnia will be consumed very quickly, but ostracods can last longer (generally less appetizing) and water lice will survive long enough to reproduce. Blackworm that have managed to reach the substrate and hide there will also have their chance.

For the rest, and especially if your aquarium is not dependent on technology (natural or low-tech), there is very little to worry about.

 

 

Finally, aquariums without fish will live perfectly fine on their own, and you will discover surprises upon your return: new critters, unexpected growth of this or that plant, etc.

 

 

In short: if you have had the wisdom to leave a good part of the control of your systems to nature, they will manage even more easily without you!