Near disaster for returning fish newbie

[golcondorus]

wow, I nearly had a disaster, a week ago I put two huge filters on my 100 gallon and took one off, left one on but forgot to relize that this would probablly cause a mini cycle in the tank until the filters got established. I usually do a 50% water change a week and I just went to do it and my hands were burning from the water, the nitrite was off the scale, I was freaking out so I frantically emptied about 75% out of there, luckilly all the fish I keep come from horrible water so much so they have evolved ways of leaving (bichirs primarilly). This will teach me to do water tests every day