How can I clean sand off my bike chain? Recently went for a ride in the forest, there were sections of sand and I can clearly see sand on my bike chain now.

How can I clean this off effectively? There are chain cleaning "machines", but they look like more of a gimmick.
You can use a spray bottle with diluted degreaser to spray down the chain and wipe it with an old towel to get most of the dirt off; or if it's really sandy or muddy you can use regular soap and water and a sponge. Then clean and lube the chain the way you normally would.

After using several different plastic mechanical chain cleaners my favorite method is also one of the cheapest. I use a small can, like a soup or a tomato sauce can, put a little degreaser in it and clean the chain with an old toothbrush.

Using the bottle is okay, but stay away from using gasoline, kerosene, paint thinner or other harsh liquids.  These will penetrate deeply into the links and will displace the lube you try to reapply, as well as creating a significant fire hazard. Some people like to use diesel fuel which is okay. In my opinion, I'd stick to a quality degreaser product.