Just wondering what is the correct amount of gravel needed in an aquarium. The guy in P@H told me an 8kg bag would be enough anf Ive just put it in but was wondering if I need more as the booklet which has come with the tank says it needs to be at least 2 inches high. At the moment everything is completly covered and looks good and is about 1.5 cm deep at the front and 3cm deep at the back as the booklet also said to make it deeper at the back?

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