I know I’m late to the party but temperature also plays a role in the oxygen exchange, colder water has more oxygen than warmer water. So upon removing the air stone like the others said it wasn’t providing enough gas exchange. (I’m guess your temp was in the 80’s)
In regards to large water changes; they shouldn’t cause problems unless you have a case of old tank syndrome. Old tank syndrome is when you do small water changes (ie not large enough water changes for your bio load) over a long period of time which can cause your water parameters to increase over time and when you do a larger change it can shock your system.
To avoid this you want to be doing water changes that fit your bio load and keep your nitrates below 20ppm. This will be a different schedule for everyone as all tanks are different
I personally do 80-90% weekly water changes on all my tanks. I recently moved all my tanks and each tank received 100% water changes and I did a plop and drop in the tanks and lost no fish.
In regards to large water changes; they shouldn’t cause problems unless you have a case of old tank syndrome. Old tank syndrome is when you do small water changes (ie not large enough water changes for your bio load) over a long period of time which can cause your water parameters to increase over time and when you do a larger change it can shock your system.
To avoid this you want to be doing water changes that fit your bio load and keep your nitrates below 20ppm. This will be a different schedule for everyone as all tanks are different
I personally do 80-90% weekly water changes on all my tanks. I recently moved all my tanks and each tank received 100% water changes and I did a plop and drop in the tanks and lost no fish.
