Walstad Tank Troubles (messed up the first post)

Hi all, here's my setup and problems, any help would be HUGELY appreciated, as I'm a beginner.

I made the daring decision to try to start a 1 gallon (mostly) wastad tank, with the ultimate goal of supporting a small shrimp population and a snail. I’ve had this tank for a year now with just the snail, to give plants a chance to grow. I’ve recently added red root floaters and 5 cherry shrimp, and experienced a prompt brown algae/ blue-green Cyanobacteria bloom that seems highly light dependent. Red root floaters are melting a bit, and minor bucephalandra melting. Shrimp and snails look healthy, although the shrimp are crapping up a storm despite the internet claiming they’re “low bioload”. I’ve attached my parameters below, sadly no ammonia measurements until I get a proper test kit.

Any advice on dealing with the brown algae/cyanobacteria (thinking 2 day tank blackout followed by shorter photoperiods after?) and decreasing alkalinity and pH (both look high, especially pH). Would additional fertilization help any of this?

Tank: 1 gallon, unfiltered, unheated, occasionally fertilized with a few drops of Thrive S  shrimp-specific, rare 20% water changes when things aren’t looking good.

Tank age: 1 year old

Substrate: Aqueon Plant and Shrimp Aquarium Substrate (Base, ~1.5 inches) Sand (Cap, ~1 inch)

Plants: Petite Anubias, 4 small bucephalandras, A small grass (unsure of the variety) Red root floaters ~14

Fauna: Black Nerite Racer snail, 5 Cherry shrimp