Welcome!
I use half dose of Excel on my 20 gallon long, planted with dwarf hairgrass, and frogbit floating at top. No ill effects to my shrimp. Initially ran CO2 24/7 at 1 bubble per 5 seconds, but shrimp seemed less active. I might try it again once my carpet is more established, but for now, Excel at half dose is working fine.
Like Pika, I only do small amounts of ferts. 1 ml of Seachem potassium, and 1 pump of ADA Green Brighty Step 3 (leftover bottle from my planted community tank), every 2-3 days. I also placed some Flourish root tabs under the soil when I set up the tank.