Ok, i got some shrimp and snails the other day in the mail and put them into my main tank where they are doing great. But i've been setting up a 5 gallon hex as an invert tank so i went and bought 5 rcs and a briggs yesterday. I did a waterchange before i put them in and added some prime. They were doing fine last night, i added half of an algae wafer and everything was eating. Then i wake up this morning and everything is dead except for one shrimp. Idk what happened. I checked the params ph=7.2, ammonia=0, nitrite=0, and nitrate=10. All the params are normal. The only thing that i can think of is that i left the algae wafer in overnight because it was already late when i put it in. Could that have caused it? I'm still adjusting to the tiny tank. I'm not used to how much small changes affect it. But if it was the wafer wouldn't the params have been off? The only other thing is that the tank most likely isn't fully matured. Its been set up for about a little less than a month. I seeded it with filter media from another tank though. Then added a guppie to keep the cycle.