I spoke too soon! I have some sort of mystery suffocation. In effort to try and lower those pesky nitrites, I did a 15 gallon followed by a 10 gallon change yesterday morning (this is a 30g tank). Now today I've got all sorts of air gulping going on, and the cheap dipstick shows the same color of nitrites. Still 1.0. I haven't had any noticeable air gulping before today even when it was at 3.0 when i first got it. Nitrates 5 and never get higher than 10, gh 150 and stays about there, kh 120 and bounces between that and 60, and pH is neutral never straying more than .2 on either side. And the ammonia has been very light lately. I changed the carbon for the first time a few days ago, the fresh stuff had zeolite in it. I put in a couple spoons of aquarium salt yesterday, but I've done that before without incident because the sore gill guy clears up a little when I do. Otherwise nothing new but fresh water. I've got two bubblers in one corner with a sponge, and another bubbler with an air stone in the other end. Plus the filter breaks up half the surface. The temp is 68F after a couple hours of the lamp being on. This is kinda frustrating when they survived years with no fresh water or good filtering, yet they're not happy while I'm babying them.