Nitrite

[Blooms-n-Bees Lavender & Honey]

Hi to you all

We're having challenges with the Nitrite.  With that said on May we cycled the at Ph. 6.4 Ammonia 0 ppm Nitrite 0 and the Nitrate 40 ppm good. Call for fish pick the fist on May 13 at day the Ph. 6.4 Ammonia .25ppm Nitrite 5.0  Nitrate 40ppm ok but I got to pick up the  fish anywhere ok.  Two days later I exchanged water in the take buy 60 Gal 1 oz. water conditioner.  But my  Nitrite will not go to 0 ppm what can I do ?  I've added some salt water to the fish cope with the highly Nitrite and yes it was not table salt.  I don't know what else I can do so is it a matter of time or is there something else I can do.  Today's readings are 7.1 on Ph.  Ammonia 0 Nitrite 2.0 Nitrate 20 ppm fish tank at 76.