You need to get a QT, and get some copper treatment, i likd coppersafe personally, get a HOB
and a heater, fill the QT with tank water, get some media from your DT and treat until it gets better. Heres how i setup my QT:
>Aqueon quietflow 20 HOB
>Aqueon 100W heater
Coppersafe made by sentry
Pretty simple, also you gotta do 10% WC
every other day to keep parameters down.