I wonder if any one has any input on using water from my koi pond to water my Bonsai? I have an over sized filter system with a water fall and settling pond. I flush my system every week where it is set up to water my tropical ground planted garden. I've done this for the past 10 years with out any known damage. Since Bonsai soil is made to move the water through the pot so quickly I would think that most all your nutriants flush past the roots, so an acculalation of ammonia should not be a problem.
If any one has experience with this then how often would I use this in comparison to other fertilizers?