Nitrite .25i 125 gallon

[Rocksor]

Safe is easy to dose with these https://www.amazon.com/Norpro-Stainless-Measuring-Spoons-smidgen/dp/B016VDB512

A drop measurement is roughly treats 5 gallons of water containing 4ppm chloramines (my tap water disinfectant concentration). I use the largest (TAD) per 50 gallons of water.

 

[iridescence]

You should test the amount of ammonia/nitrite in your tap water. Most people will have .25-.5 ammonia straight from the tap, so personally I don't believe that you should do daily water changes (unless you're getting 0 ammonia/nitrite straight from your tap) but rather just let the tank cycle with your fish since you're already getting ammonia/nitrite readings of .25. The reason being you're just adding the ammonia back from to the tank after removing.

-Add some type of beneficial bacteria in a bottle (turbo start 700 is hands down the best one)
-Don't feed for a week
-Redose prime every 24 hours to detoxify ammonia/nitrite.
-Don't stress, they'll be fine.