Using a household timer in fishkeeping.

Using a time relay (timer) in aquarium hobby is nothing new. Automating the switching on/off of the lighting fixture is usually the first task you delegate to a mechanical or electronic assistant. However, the scope of timers in aquariums can be expanded. Basically, according to their design, timers are divided into two groups: mechanical (or daily) and electronically programmable (or weekly). The first thing that comes to mind for every aquarium owner who has to go to work regularly is to connect the aquarium light to a timer. It must be said that both mechanical and programmable versions handle this task equally well.

Electromechanical time relays are quite cheap and easy to set up. They differ from each other by having a switch that allows the plugged-in electrical appliance to work directly, bypassing the timer’s settings. When you need to turn on the light or air pump directly without pulling the plug out of the timer and plugging it into a free outlet, you just need to move the lever, and the timer turns into a regular power source. This may be necessary when the timer program has currently turned off the light, and you need to look at something with the light on.

The simplest electromechanical timers only have a dial (scale) on which the time for closing and opening the electrical circuit is set. A timer without such a switch loses a lot, because you would have to pull the plug out to directly turn on the device you need to operate.

Almost all electromechanical timers are programmed the same way. They have a scale where the closing and opening times of the electrical circuit are set by pushing pins out or in. Usually, the minimum interval (one pin) is 15 minutes. This is a minor drawback, since a fully digital timer has the ability to switch on and off every minute. But when using a timer for aquarium equipment, we won’t need that.

By pushing the plastic tabs down during the time period when electrical appliances should be on, we set the operating schedule for our aquarium light or air pump. The disadvantages of electromechanical timers are: 1. The set program is identical for every day. 2. When power goes out, the timer lags by the exact duration of the power outage. 3. Some models tick like a mechanical alarm clock.

Electronic (programmable) timers differ from each other mainly in exterior design and a few features. Some have daylight saving time transition, others have motion-detection features (turning on when approaching the device plugged into the timer). All electronic timers are equipped with a switch that allows the connected electrical device to operate directly, bypassing the timer settings. Electronic timers have internal batteries that prevent the set program from resetting during a power outage. As soon as power returns, the timer runs according to the set program.

Disadvantages of electronic timers: 1. Internal batteries are not eternal, and eventually their lifespan will expire. If you fail to get new ones and replace them, the timer must be discarded. Advantages of electronic timers: 1. A separate program can be set for each day. 2. Programs can be set for multiple days, e.g., only for the first or second half of the week. 3. Programs can be set every other day. 4. Programs can be set for any single day. 5. Compared to mechanical timers, there are no plastic tabs, no gear mechanisms, and no ticking sounds resembling an alarm clock.

The timer itself will turn a device on or off. For example, it will turn on the aquarium light in the morning and turn it off in the evening. It will turn on the air pump at the right time. It is advisable to turn on the aquarium light when daylight from the window fills the room and the fish are already awake. But how can this be done on winter days when it gets light late, and we have long left for work? Or, for example, if we stay out late visiting friends, who will turn off the aquarium light without us? Leaving for the dacha or vacation — who will turn the aquarium light on and off? We want the aquarium lighting to match a proper daylight period (approximately 8-12 hours of being turned on) while avoiding continuously running or off lights. In such situations, a timer is irreplaceable.

Its use makes aquarium maintenance easier. It helps properly maintain daylight hours without extra lighting time. Higher aquatic plants, fish, and reptiles quickly get used to and adapt to time-stable processes, and a rhythmic cycle spares them unnecessary stress. Having several timers makes the task even easier. The second timer will control the air pump, turning it on and off at the right time. In some aquariums, depending on the fish and plant load, aeration is required 24/7. Working continuously, many air pumps quickly wear out, exhausting their lifespan. A timer can be programmed to give rest to one air pump while the other runs throughout the day.

If you have multiple timers and basic electrical skills, you can even simulate sunrise and sunset by gradually turning lamps on in the morning and off in the evening at 10-15 minute intervals. There is no special need for this, but it looks quite spectacular and unconventional. Moreover, such an algorithm will help preserve the health of exceptionally nervous fish, especially wild-caught specimens, for whom abrupt lighting changes cause panic. This way, we help them adapt to new conditions and reduce stress. Many have probably read about the impact of the “moon phase” on the spawning of certain fish. Here, a blue bulb or a special “Night Glo” lamp along with a programmable weekly timer will come in handy. Set the program and sleep peacefully: the “moon” will rise and set just like the “sun” without our participation.

What else can and should be automated? It wouldn’t hurt to look into thermostats and connect them through a time relay. The fact is that, just like in nature, we should maintain daily temperature fluctuations of a few degrees. This allows fish and plants to reduce energy expenditure at night, ensuring proper rest. Naturally, increasing the thermostat’s “idle” duration at night should be done gradually while monitoring morning aquarium temperatures. Owners of small tanks might not need this advice, especially if the room is cool.

Timers are also extremely useful in continuous-flow (“prowtok”) aquariums. Setting up a water-changing system (with a daily replacement of 10-15% of water) is quite troublesome, and few dare to do it, even understanding the benefits it brings to fish. Attempts to replace a third of the water three times a week in a two-ton aquarium setup led me to think that this process must also be automated.

There are many solutions, but the simplest is to connect an aquarium water pump via a timer to drain water into the sewage system through a hose. The frequency and duration of pump operation depend on the tank volume. Fresh water is refilled via a float chamber placed inside the aquarium. A standard plumbing float valve can easily handle this task. By the way, this is one of the safest methods. Whatever the design of the continuous water flow in your setup, set the timer so that it adds water when you or family members are at home—just in case. And turn it off completely when you leave for the weekend.

What NOT to trust timers with.

First of all — filter operation. Bacteria inhabiting the filter media and participating in the nitrogen cycle need a constant supply of oxygen. If you turn off the filter at night to avoid noise, you might sleep better, but some fish might never wake up.

I wouldn’t interrupt the nighttime operation of the air pump either. Unfortunately, relatively quiet models are quite expensive, and most of the noise comes from bubbles breaking the surface. However, aeration at night, when plants consume oxygen and release carbon dioxide, is even more necessary than during the day. You should either completely abandon the air pump (which is not always possible) or put up with the noise. Switching to a “nocturnal lifestyle” is out of the question. Disabling “bubbles” during the day is possible, but besides negligible electricity savings, it brings no positive results.

Automatic fertilizer dosing systems for plants have proven to be quite reliable. Many methods rely on timers, so if desired, you can build such a device yourself. But in my opinion, it is better to use a ready-made one.

There is only one question left that I would like to draw attention to: how to properly connect a timer? The fact is that a time relay will serve faithfully for years only if the following conditions are met:

• If the timer has a Euro-plug connector, plug it only into a Euro-socket without using various adapters;

• If possible, connect the timer (and all aquarium equipment) through a surge protector / power strip;

• When using a single relay for multiple aquariums, make sure the load does not exceed the rating specified in the relay’s manual.

There are many timer models with diverse designs. You can find German, Finnish, Polish, and Chinese timers (and surely others). The price naturally depends on the manufacturing country. Quality… well, that’s a gamble: if you’re lucky, even a Chinese one will prove durable and high-quality; if fortune turns away, even German engineering won’t save you.

Water filtration filters. A filter is an essential part of an aquarium.

Automatic fish feeder. DIY automatic feeder.