Substrate substite?

Aquariums are not a big hobby where I live, and planted tanks even less so. I want to set up a 125 gallon planted tank (just some Amazon swords, apongeton and java ferns) and use sand as the substrate. I cannot find sand in the aquarium shops in the nearest metropolitan area, only finer than average "natural" gravel, but still far from sand. Can I use the sand sold for sandboxes (too fine?) or go to the gravel pit and buy the sand used to mix concrete? The tank will be for D. Compressiceps and H. Moorii, so I'm not worried about raising pH. Any suggestions? Also, I've used Tetra Initial Sticks in another planted tank and ended up with a horrible beard algae problem. This is the only tank (out of 18) I used the Tetra Initial Sticks in and the only tank with the beard algae problem, so I'm assuming that there is a connection, although I don't know that for sure. Like the sand issue, I don't have access to laterite or some other substrate additive (although I suppose I could mail order something) and the Tetra Initial Sticks is the only product I can find within a few hours drive. I'd appreciate any advice I can get. Thanks.