Every year, the summer comes quite suddenly and so regularly the question occurs, how to keep the temperature in the tank stable.
Considering, that in the most tanks the water temperature is already at 25°C without any heating (but heating of the technical equipment) at a normal 22°C room temperature, the tank temperature rises quickly above with increasing room temperatures. The same temperature difference on a normal day (like an addition of for example 3 degrees above room temperature) of course adds to the rising temperature as well.
Skimmer, flow pumps and other pumps as well as pumps for calcium reactors and filters are rather inefficient and therefor add much heat energy to the water.
Last summer, I lost some corals because of the temperature – for example Zoanthus and disc anemones, which already show problems over 27°C. And this could show up also delayed, if your tank temperature is already back at normal.
So preventing temperature problems is most important. If the temperature is already above 28°C, it is critical and could cause coral dying.
What are the possibilities to cool down your aquarium tank?
1. Cooling unit
I also had a Aqua Medic cooling unit during my summer holidays last year. Sure, it’s a good but expensive solution and cools down your tank quickly. And you have to keep in mind, that the extracted heats up your room as well.
Ideal is a safe and cool place in the outside. A cooling unit is unlikely to be worth at most tanks and especially in Germany with just a few hot summer days.
2. Fans and ventilators
Fans are a safe and for most of the tanks cheap, flexible and effective way to cool down a tank. The number of fans and the size has to be adjusted to the tank size and dimensions. I refer to my article, where I modified my Grotech fan. With this modified fan and a temperature control, I’m able to cool down my tank within 3 hours at a room temperature of 26°C down to 25°C water temperature.
The cooling works in this case when the air blows over the water surface (this effect is familiar if you stand in the wind after bathing).
To avoid having a cool tank but ending up as a nervous wreck and tinnitus, you should buy more expensive fans or large and quiet fans, which are mostly used in computers. I have 2 fans with 12cm at my tank. Since they turn much slower and carry a lot more air, they are very quiet and effective.
In addition, you should always have a Auto Top Off because the evaporation increases (I need 20l / 3 days in summer).
A good surface flow has an additional cooling effect.
3. Ice Bottles, Refrigerator etc.
In small Nano tanks there are often frozen PET bottles used. This has a very short-term effect and is highly inefficient. I’ve also heard of DIY-projects, where the tank is connected to a refrigerator and the water is cooled down inside. Creative, but mostly not useful.
4. The luxury solution humans and animals is to cool down the entire room with air conditioning.
In the end, in our latitudes, a Fan-solution certainly is the cheapest way to cool down your tank. For larger tanks or in warmer climes, the purchase of a cooling unit definitely makes much more sense.