You will usually start getting snail population issues when you are over feeding. Cut back feeding to every other day or so, and keep manually removing the snails. Snails are a fact of life much of the time in aquaria, but they are rarely a problem unless you are creating an environment that heavily favors them, ie, excess food and detritus.
I also don't recommend loaches. Many loach species will need a small school to stay happy, and there are very few that belong in a tank that size, unfortunately.