Aquarium gravel

What should be used for the substratum, (the bottom of the aquarium zone, usually consisting of sand and gravel in which plants anchor their roots.) gravel or sand, the answer will depend on what exactly your goal is.

No matter which substratum you decide on, under no circumstances should it derive from a salty environment (e.g. seaside) or limestone quarries. You must use only substratum derived from rivers or quarries formed in river beds. Or more simply buy it from a specialized store.

Before introducing the substratum to the aquarium you must wash it several times, until the water runs clean, you should then boil it for 1- 1½ hours, and then wash it again thoroughly.

Gravel

The advantages of gravel are that it allows for uniform planting. Even after the first days of introducing it the aquarium it offers great aesthetics, it allows nutrient substances such as nitrates to easily access the plant roots and it is easier to clean the water than when washing with sand. 

There are also some disadvantages with aquarium gravel, it can get loaded with algae and stop reflecting light into the fish tank, the dirt deposited under the gravel can not be eliminated other than by general cleaning of the whole aquarium (every 4- 6 weeks).

Luckily nowadays you can buy fast cleaning kits for cleaning the fish tank gravel, this is based on an automatic start and fast turn-off system. The device is triangularly shaped which allows cleaning corners of the aquarium, and can be connected to an exterior filter.   

Sand 

There are several advantages in using sand as substratum for your aquarium: it looks bright, secures the plant roots, and allows for the general tank dirt such as food, plants particles and fish excrement to be guided towards the filter and evacuated.

The right choice for your aquarium substratum will depend on your choice of fish. Some fish feed themselves only from the bottom of the tank and have the tendency of grubbing into the substratum. It is therefore best for them if the last layer of the substratum is either very fine gravel or sand.

If you intend to breed fish which multiply through egg lying you would be better off choosing rough gravel so as to allow the eggs to slip between the gravel pieces. Many fish have a tendency to eat their own eggs so, the gravel will serve as a barrier.

Background and substratum advice  

 Do not use whelks or sea shells as decor because they roughen the water.

 Do not use limestone sand unless your fish of choice requires it.

 Do not use artificially colored aquarium gravel, not only will it look artificial it can also damage the fish.