Gravel in pocket

There are several brand and varieties of gravel to choose from. I would be more than happy to post some of the more preferred brands here for you; however the choice is not so simple. Make sure you know what kind of gravel you need for the type of tank you have.

http://www.petsmart.com/product/index.jsp?productId=3577442

http://www.petco.com/product/112362/CaribSea-Instant-Aquarium-Crystal-River-Gravel.aspx

http://www.aquariumguys.com/gravel.html

It is most likely that the gravel you are using contains calcium and magnesium. This will ultimately cause the pH level in your tank to rise. You should use an inert gravel such as Swell Harlequin Gravel.

http://www.swelluk.com/aquarium/substrate-1695/gravel-1829/swell-harlequin-gravel-blue-376469.html

Most gravel sold today are pre-washed although gravel can accumulate grit in transit as the grains rub together therefore it is advise to wash them.

The reason for that is because many colored gravels are made from white dolomite which contains calcium and magnesium. In order to maintain the PH level you should get inert gravel.

Yes, if there is no gravel in your aquarium, there are not bacteria colonies because they can only thrive in gravel environment, therefor you need to replace the water more often.

The gravel provides a home for beneficial bacteria which help dispose waste products in your aquarium, and the useful colonies of bacteria can only thrive in gravel.