I have been using my well water for water changes for over 2 years with no issues, but noticed my Dayi eel head jerking and swimming in circles yesterday. Then he would stop and return to normal but did not eat. I did a quick water change although I did 50% only a week ago. I tested the new water while I was at it and it tested 40 ppm for nitrates. I’ve had no issues with sick fish but knowing the eels are more sensitive I decided to just check the well water and I’m glad I did. I don’t know if the water has been at 40 ppm for sometime or if this is new but like I said there has been no issues for a while. I need advice or methods of doing 100+ gallon water changes effectively from water sources somewhere besides their home. My only two options I’ve come up with so far is lugging a giant tub around in my truck and spending a fortune on water at the store, or adding an absurd amount of houseplants to keep up with my bio load. I have several large Pothos vines growing out of the tank already but not nearly enough for a 300 gallon system. Thanks in advance