Thank you Deeda. To make matters worse I went to walk the dogs so I put on some 25 year old dish detergent that smelled musty..but I didn't have anything else to keep the mosquitos away. When I cam back into the house I did some chores and then I found something that would go nice in the 75 gallon tank for the fish. So I put it in the aquarium. To my horror I realized that I still had that musty old dishwasher detergent on my skin!! 5 min later, I shut off the canister filter. Should I try a 70% water change???Deeda said:Yes that is just fine!!
If you aren't adjusting your tap water parameters for the aquarium by adding buffers or similar, you could just do 50% water changes at one time as many members already do so. A lot may depend on your source (tap) water and if you have sensitive fish. If your tap has chlorine or chloramine, just add that product as you are adding new water and dose for full tank volume, not for the amount of water changed.
For example, I have a private well with hard water so I just change 50% weekly on any of my tanks whether they are Malawi, Tanganyika, cherry shrimp or even Tetras or similar tropical tanks. I just make sure to use hot and cold tap adjusted to near tank water and use a hose to fill directly since my tap water is untreated, no chlorine or chloramine.