I've gotton a hold of a 180 gallon tank. And I went to a landscaping place to get the gravel since I did not want to spend $300.00 USD on gravel so instead it was $22.50 But the smallest gravel they had was kind of large some as much as 3/8 of an inch across and about 1/3 of it pea sized. Is this cause for concern? Because the food might sink between the pieces of gravel? Any help greatly appreciated.