I'm using Neptunes Harvest, but honestly I'm beginning to think Microgreens really dont need fertilizer. I also learned to take what I watch on YT with a grain of salt and not rely on everything they say.
https://www.amazon.com/Neptunes-Harvest-FS136-Seaweed-Fertilizer/dp/B00BSULVN6/ref=sr\_1\_9?crid=633TXWKKZ6B6&keywords=neptunes+harvest&qid=1653694254&sprefix=neptunes+%2Caps%2C82&sr=8-9