welcome to fishlore!!!!
do you have an airwand or stone to circulate the water on the surface of the tank? your tank is huge and with my 75 gal, i have to keep 2 bubble wands in it to keep the surface water agitating ... ...did he have it prior to adding the buffers ? ..was his tank the one treated for
ICH? and having a
nitrite reading, means the tank is in a mini cycle for some reason..so that could be affecting him also...if you can find some stress coat+ or prime, (they both detoxify the nitrites to keep him safe, and still help finish up the mini cycle )with daily water changes to get thru the mini cycle, should help....