When is too many plants?

It's up tp you really. You could being them until there is no allowance for fish!! It absolutely depends on how abundant time you are accommodating to absorb on fertilizing, pruning, etc. I don't anticipate there could technically be too abounding plants.

One of the important benefits of your pond plants, algae is their competition nutrition. Because of this, they are effective in helping to keep the pond of algae. Another important benefit is that they use your koi fish waste as fertilizer. Thus helping to eliminate unnecessary another guest house in your pond.