I just upgraded my 4 gallon cube tank to a 16 gallon bow front with 2 fluval c3 hob that was from my another 16 gallon bow front which I upgraded to a canister. Now my shrimp are dying.

Little info.

Got the tank setup last Friday with a big drift wood as a center piece with bunch of live plants to go with it, pool filter sand, seachem root tabs, 100 watt heater (not plugged in do to hot weather) aqueon modular led light. Use Prime to condition the water.

Added the shrimp on Saturday and spent 2 hours with a flashlight and shrimp net trying to catch the babies. Finally got them all. Plus my 2 Dwarf crayfish and my handicap baby swordtail. Added 2 cory julie catfish and 4 amano shrimps for cleanup duty. Everything was fine until I touch the tank on Monday.

My hob impeller got really noisy. Took each one apart to clean the impeller and add silicone grease (no petroleum additives) to the impeller shaft to keep them quiet. Added 2 gallons of treat water into the tank that I lost. Took some out to keep the sponge and bio media in when cleaning the hob.

After this, my cherry shrimp starting dieing. Lost 8 in a role and half the next day. Did a massive water change but losing 1 or 2 a day still. Crayfish, amano shrimp and corys are doing fine.

Here is my water parameters, API Master test kit that I use

Water temp is around 80 to 82 (been hot lately)
PH 7.6
High PH 8.2
Ammonia 0 ppm
Nitrite 0 ppm
Nitrate 0 ppm

Any ideas to what happen to cause half of the cherry shrimp to die?