Switching salts

I have just changed salts since geting my new RO unit.
When i collected ready mixed salt from lfs it was rc but if i just got plain water i would mix up my own with io i now use HOBBY MARIN SALT as dose my lfs and the only problem we are both experiencing is a higher nitrate reading. Although i have an exenia which has been closed for over a week now but an orange tree coral which has responded fantastically.
 
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