You can get a Diverter Valve for RO DI Water Systems
or a Garden Hose / Laundry Hose Adapter for RO/DI systems
or a Kent Reverse Osmosis RO Garden Hose/ Spout Adapter
and then get a garden hose adapter for your kitchen faucet. That's what I do.
There are several garlic preparations available. I use GarlicXtreme which is an extract. You put two drop onto food and place it in the tank.
The problem you have now is that you have Ich in your tank. It can now infect all other fish in the tank. You really need to get all fish into a QT tank and treat there (hyposalinity IMO
) while the main tank remains fallow of fish for 6-8 weeks.