You have been getting the best advice - - - Change change change the water. Nothing is better than fresh clean water.
Don't treat with chemicals when you don't have to - - The pet store just got you to spend more money when you need to only be doing more work.
Change most of the water, fill with new treated water.....repeat at least twice a day and post your test results prior to changing the water
edit: by treated I only mean with a fresh water conditioner to remove chlorine - no other chemicals or salt should be added
Don't treat with chemicals when you don't have to - - The pet store just got you to spend more money when you need to only be doing more work.
Change most of the water, fill with new treated water.....repeat at least twice a day and post your test results prior to changing the water
edit: by treated I only mean with a fresh water conditioner to remove chlorine - no other chemicals or salt should be added