Okay, you're probably not going to like this answer.
If one fish has ich on it, the WHOLE tank is infected and needs to be treated. I just went through my first bout of ich and let me tell you, it wasn't pretty.
I raised my temp and added salt and they did fine. I called the fish store and asked if it was safe to add fish (after the ich was gone) before a water change to clear the salt. They flipped and told me to buy this ich treatment. Well, the ich treatment killed HALF of my fish in 24 hours, including my prized angel.
I would recommend staying clear of medication unless absolutely needed. To clear the ich naturally, you have to do to things: heat and salt.
Crank up the heat to 88 degrees. Turn the heat up 2 degrees an hour. I know it's high, but fish can live with that temperature for up to 2 weeks. It's pretty incredible.
Next, I know you don't want to hear it, but salt IS the best treatment. Heat simply makes the cycle of the ich go faster so it leaves faster, but salt will kill the ich in the process. If it's the loaches you're worried about, move them to a hospital tank and treat them with medication.
Also, your nitrates are pretty high in that range. They should be under 10.
I'm sorry to have to be bearer of bad news to you
I wish you the best of luck with your fish!