Inspiring! I'm just starting with my Walstad tank. Used 55 gallon for 20 bucks. I didn't build it from scratch like you, but I did re-seal it!
Couple questions if I may:
What is bdbs? you said you used that to cap your soil.
Why did you use the plastic grid on the bottom?
Why were you adding ammonia? Is it because you had no fish yet and the plants and bacteria need it as nutrients?
My plan is similar to yours. I will likely turn the light intensity down. Too much could be why you had some algae? Not sure. Maybe you did have the light intensity down. I don't want to assume. Also, the way I understand it, it is best to start out by planting heavily to start, so the plants out-compete the algae for the nutrients. Please keep sharing your experience. I am learning from it.