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Self-Improvement & Hobbies

Aquascaping – rocks

An aquarium with rocks, rocks! Learn how to use them to beautify your aquarium
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Aquascaping – rocks

Rocks are a key ingredient in any aquascaping effort. Properly chosen, prepared and positioned, they can transform an otherwise clinical setup into an attractive replica of actual biotopes found in nature.

However, be mindful that not all rocks are “born” equal. Before you dump any old piece you found by the roadside into your tank, check to see if it is safe for your aquarium. The kinds of fish and plants you keep will, to a certain extent, determine the types of rocks you can use.

Choosing rocks

Generally, the best types of rocks for freshwater aquariums are collectively known as inert rocks. This group includes rocks like basalt, obsidian, coal, quartz, sandstone and shale. As its name suggests, this class of rocks does not affect water chemistry, and is therefore a safe choice for freshwater aquariums of all sorts.

In contrast to inert rocks, calcareous rocks alter water pH and raise hardness levels. Varieties commonly used by aquarists include chalk, limestone, marble and tufa. Calcareous rocks are good for hardwater or brackish aquariums, and are really handy when you want to raise hardness and pH without resorting to chemical treatments.

Testing your rocks

If you’ve picked up a piece of rock from somewhere, and are not sure whether it is safe for your aquarium, here’s what you ought to do.

Fill a bucket with water from a source that you’d normally use (probably the tap for most of us); better still, use old aquarium water. Test for pH, hardness, nitrates and phosphates. Put the rock into the bucket, let it soak for a week or more, then test the water again. If subsequent readings do not deviate much from the original readings, the rock is not likely to adversely affect your aquarium.

Another test that aquarists like to use is the vinegar test. Put a few drops of white vinegar on the rock. If the solution foams, the rock is calcareous. You’re probably better off not using that piece of rock, but if your intention is to alter water chemistry, it is a possible candidate.

Preparing your rocks

Once you are confident that the rock you’ve chosen is aquarium-safe, just dump it into the tank, right? Not so fast! You need to disinfect it first. Who knows what manner of pathogens are residing within its crevices?

Start by brushing and rinsing debris off the rock surface. Then cook it in hot water, and allow it to dry in the sun before placing it in your aquarium.

Using rocks

Rocks are very useful for dividing the aquarium into pockets of space, which fish of a territorial nature can claim as their own. This reduces the chances of fighting and bullying. Relatively small pieces of rock can, for example, be arranged to form a circular arc having a tank corner as the centre, and bounded on both sides by tank walls. That leaves a neat little quadrant for a mated pair of angelfish, for example, to claim as their own. Over time, other fish will learn not to intrude into this quadrant, and peace shall prevail!

In addition to serving a functional purpose, rocks can also be an aesthetic delight if you use them well. Dramatic effects such as rockfalls or a scattered appearance can be achieved with a few large rocks surrounded by smaller pieces or chippings of the same type of rock. If you’re thinking of building complex rock structures, you may need to glue the individual pieces together with silicon, so that they won’t fall off and hurt your fish.


Aquascaping – plants