Leaving for a holiday? How to prepare your tank

Introduction

There are a number of considerations for planted tanks when the aquarist plans to go on vacation.

From a safety standpoint, it is important to have a good setup where the tank/equipment is of good quality - equipment failure can be catastrophic if there is no one around to fix problems. Having a well organized system with electrical points protected from water is also highly recommended.

How sensitive planted tanks are to being left alone depends largely on 2 main factors: plant selection and light levels. Tanks with fast growing stem plants or demanding plants that require more care are more at risk. On the other hand, tanks with mainly mosses and slow growing plants can easily survive for weeks without much intervention.

Light is the other main factor, as it is the main driver of growth, and tanks with higher light levels tend to have greater fluctuations in their microclimate: faster growing plants fill in and crowd out slower growers, and stronger light tends to trigger algae.

A high light tank with finicky growing plants needs more preparation if it is to be left unattended for a few weeks. A tank with only light mosses and epiphytes may require no preparation at all.

Above is an example of a tank with mostly fast growing stem plants that will quickly become overcrowded if left alone. The higher light levels will also cause severe algae problems if, for example, the CO2 system runs out while the aquarist is away. The nutrient demand of this fast-growing stem plant tank is also much higher than an aquascape with slower-growing plants. This type of tank is more susceptible to disturbances if left alone for long periods of time. One of the most important things to do before a trip is to trim/replant the stem plants down to 3 or 4 inches and let them recover during the trip.

This low tech tank uses mostly slower growing plants such as Java fern, anubias and mosses. Even the carpet, Lilaeopsis brasiliensis, will grow slowly in a low-tech environment. Without a CO2 system to worry about or high lighting to potentially trigger algae blooms, this tank can be left alone for 2 to 3 weeks with no major problems.

This tank is very different from the other example above. In that exact example, we would do a water change, dose the water column with nutrients for half a week, and then leave the tank as is.

Automation

As equipment gets cheaper over the years, many of these options are worth considering, especially given the low cost of implementation.

There are a number of systems that can be automated. Automatic fish feeders are easy to use and set up, although most fish should be able to go several days without food. Automatic liquid nutrient dispensers are also widely available now that they are popular in the reef hobby.

Power timers are easy to program and are a common method to control CO2 regulator solenoids. 

Auto-dosers inject a programmed amount of liquid fertilizer into your tank at preset intervals. They are quite affordable by today's standards and are easy to set up.

Most tanks should be able to go a couple of weeks without liquid nutrient dosing - however, folks who are growing particularly finicky plants or want a convenient solution to skip manual dosing anyway can consider setting up liquid autodosers.

Similarly, there are auto-top off systems that can be set up to refill tanks as they lose water to evaporation, but if you can get a friend or family member to stop by, that would also be an easy solution.

Most aquarists should already have lighting and CO2 systems on automatic timers. If not, simple power timers will work - there are units that come with wifi or blue tooth connections for easy programming. These are some options where automation is available.

• Automatic light and CO2 timers (every system should have this by default)
• Automatic fish feeders (recommended if leaving for longer than 2 weeks)
• Automatic liquid fertilizer dosers (recommended if longer than 2 weeks, or if running higher nutrient demand tanks)
• Automatic water top offs (recommended if leaving for longer than 2 weeks, alternatively, get a friend to come in to help

7 adjustments before leaving:

Generally the aim is to slow growth down, so that aggressive growers do not overcrowd and shade out plants beside them. 

Light

Light is one of the main drivers of growth, so reducing light levels to the minimum required prior to travel is one way to slow growth and prevent algae outbreaks. For tanks running very high light (150++), lowering the light levels to around 80-100 umols of PAR is a good compromise. You may lose some plant coloration, but the tank will be much more stable overall. Plant pigmentation is very easily regained when light levels are increased upon return, so this temporary downward adjustment should not be a major concern. Lighting times can be reduced to 6 hours.

CO2

CO2 injection rates should be kept stable (unchanged) as drastic changes in CO2 rates will cause significant physiological changes in aquatic plants that may be difficult to recover from. Just make sure your CO2 tank is sufficiently full before you start your trip.

Temperature

Cooler tanks are more stable because both plant and microbial metabolism slows down. However, animals from tropical regions may not like the dip. For those with temperature control and animals that can tolerate lower temperatures, lowering the temperature to 20-22 degrees Celsius is more stable than higher temperatures (i.e. above 26 degrees Celsius).

Fertilisation

Auto-dosers can be used for those who don't mind setting up the system. They are not a necessity as most tanks that are not growing at super speed (mainly EI users) can go without fertilization for a few weeks without any problems. This is especially true for tanks where the plants are mature and an Aquasoil substrate is used to provide nutrients to the rooted plants. We recommend dosing a half-week's worth of fertilizer before you leave and then just letting the tank run as normal. If you are going to be away for more than a few weeks, and if you have a high demand tank, setting up an automatic nutrient dispenser is the simpler solution. For low-tech, low-demand tanks, you can just let the tank sit out without major problems.

Livestock

Fish in mature tanks can usually go a few weeks without food. If not, set up an automatic feeder or have a friend stop by every few days.

Evaporation

Evaporation can be significant over a period of several weeks. You can test this in advance by checking how much the water level drops over the course of a week. This can be significant for CO2 injected tanks with outlets just below the water surface - as the water level drops and the outlet rises above the water level, you will get a lot of off-gassing of CO2 due to the increased agitation. A DIY water top off system can be designed, a commercial water top off system can be installed, or you can get a friend to stop by at the end of the week for longer trips.

Plant husbandry

In tanks with many stem plants, we would usually do a deep trim or replanting of the stems, cutting them down to an extremely short height (3-4 inches) and letting them recover slowly over the next few weeks. Similarly, other plants should be spaced so that they have enough space to grow into over the next two weeks.

This is the maximum height that stem plants should have before going on a 2-week trip. However, the tank as a whole is already quite crowded, especially the carpet.

To prepare this tank for a 2-week vacation, we would trim/replant the carpet to the point where we can see the aquasoil, and we would thin out the stem plant density by about 50%.

For this tank, we would trim back the moss a bit and shorten the stems even more. We would also turn down the light significantly in this aquascape to prevent algae. Other than that, this tank is easy to leave alone. However, there is one obvious weakness: the CO2 diffusor can come loose and mess up the CO2 levels. This is one of the main weaknesses of in-tank diffusers compared to in-line diffusers.