Hey there. You don't say anything about plants or shade. That is usually the best way to reduce algae. I am not certain why the frequent use of the pond enzymes. That should be a very occasional addition, if ever. Your pond is more than 100 gallons. You need to add in the water that is in the waterfall and stream. That could be a substantial amount of water. You also don't say how old the pond is. Has it had time to go through the normal start-up cycle? You may be forced to go to the use of a UV light. They come in small sizes at a reasonable cost. Lava rock and pea gravel are not always the best choice for filter material. I have had it become a haven for algae growth. Try topping off the filter with quilt batting (in sheets). The addition of hydrogen peroxide can be helpful to kill algae.

The FAC section for the pond forum references an excellent article by Norm Meck about the control of algae. I post a link below. For a standard Google search type in green water Norm Meck. There is an addendum to the the original article that is helpful.

Conversations is usually the place where we talk about anything and everything other than our ponds. More people, who can respond to your pond questions, will see your post on the discussions section. Hope this has been helpful.

Here is a link that might be useful: Green water