Texas face turned black

[Sacklunch]

ive caught trout that have a half black face im glad i have a reasonable answer for it now... i was just going to assume it was a magic fish

 

[Turion2112]

Usually I do weekly or Bi- weekly same as you do, but I was busy and was not able to change the water as I like to. The tank is well filter with 2 filters and even though I neglected it for a month the ammonia and nitrites were still at 0, nitrats = 40. The ph will drop if I do not add the buffer to it. If I just do water changes and add new water the ph will drop to 6.2 in no time. Water temp is 81.9

 

[Sarah88]

oh ok yeah thats really weird that it drops like that but have something to do with how its treated by the city or something, but at least you fixed it now and your tex got better, now you know how to fix it if it happens again. and i wonder if that might have also been the cause for that festae's face change in one of the posted threads