Stagnant Aquarium Water
I have a 10 gallon fish tank, which I did a water change awhile back. I saved 4L of the 'waste water' to feed my plants. I forgot about the jug and needless to say it's been still at room temp, stagnant and closed for about a month.
Would it still be safe to use in my plants or should I use fresh aquarium water next time I change the water?
I am growing Cayenne peppers, and this will be my first time using aquarium water with plants.