Aquarium Substrade?

[ugot lucky]

Hello,
Im creating a freshwater goldfish tank and I need to know what type of gravel will be the best for the job.
I know that goldifsh need rocks that will be able to pass in the digestive tract but the question is what kind.
If you know of the best gravel that is not very expensive please tell me and how much would I need to cover the floor of a planted 55 gallon tank.
All comments will be appreciated and will be very helpful.
THANK YOU!

 

[Skins]

You will need about 29Kg of natural gravel which is med to lge in stone size. Goldfish have been known to swallow the smaller size gravel.

Keith.