If Thrive,Thrive+ and ThriveC are safe for shrimp then why do you have a shrimp safe version(ThriveS)?

This comes down to a question of the focus of the tank. If shrimp are the focus of the tank then you want to go with ThriveS. If the focus of the tank are plants then go with Thrive, Thrive+ or ThriveC. If you have ever had a shrimp focused tank before then you know the importance of water stability. Water changes are important, but they are normally small and infrequent.

ThriveS is designed to not increase the necessity of water changes above what would normally be done with good tank maintenance on a shrimp tank. While Thrive, Thrive+ and ThriveC are shrimp safe they are concentrated to provide the plants with all the necessary nutrients, which also increases the need for frequent larger water changes.