Ich in a shrimp tank and 1 pleco.

I am using Kordon Ich Attack in my tank right now to treat a Brochis with Ich.
It is an organic compound that is safe for inverts and all fish, plants, too.

You do need to crank the heat up. Gradually, over a few hours, bring the heat up to 86 degrees F, and the dosage on the bottle says "1 capful (5ml) per 10 gallons twice a day, but can be given three times a day, which is what I'm doing.

The heat speeds up the life cycle of the Ich protozoan so that it reaches the free swimming stage, at which time it is vulnerable to the medication. That's why you want to be diligent in dosing the tank to make sure the concentration is right.

I would continue to test for ammonia and nitrites with a liquid test kit, very important as the test strips are unreliable and inaccurate, to keep ammonia and nitrites as close to 0 as possible. That means you will have to do water changes to keep those numbers down. Just repeat the dose after the change, and be sure to make the replacement water the same temp as the tank water.

You also need to vacuum the substrate really well when you do the water changes so you get any cysts that are in the gravel/sand.

Continue to treat the tank for several days past the time when you see the last speck on the fish. I'm going to treat my tank with Ich Attack for an additional 10 days after I see no more specks, just to be safe.

Once your Ich is cleared up you need to stay on top of the water parameters to keep the ammonia and nitrites as close to 0 as possible. Once your tank is cycled the water changes will be less freguent, say once a week. However, I have a 10 gallon also, and they are subject to spikes so you have to very careful to monitor the parameters and keep the water clean.

Prime is a great water conditioner because it detoxifies the ammonia and nitrites, while not interfering with the cyle process, and the detoxification is good for about 24 hours, which helps the process be less frantic. Gives you some breathing room to do the big water changes within 24 hours of dosing the tank.

When you have a spike you can do an emergency dose, which is 5 times the usual dose, and it will save your fish and your sanity. You still have to do water change to remove the ammonia and nitrite, but for 24 hours it is safe, giving you time to go to work or bed or whatever.

With the increase in temperature you will likely see a lot more specks, and not just on the pleco. Things usually look a lot worse before they get better. Don't panic, it's just the heat speeding up the life cycle and causing the protozoan to be visible where it already has attached to the other fish.

The specks will drop off in appx 4 days with the temp at 86. They will drop to the substrate (reason for vacuuming the substrate thoroughly with water changes) and form cysts that, after a period of time [can't remember exact timing on that step] the cysts will rupture and release thousands of the free swimming protozoans. This is when they will be killed by the med.