Shrimps dying, pls help

[chorkeat]

Past few days my adult shrimps (tiger, CRS, Cherry) is dying at a rate of 1-2 pcs per day. They are all in the same 2ft tank.

Main suspect is the weather which is pretty hot lately but I cant help it as I am using 2 fan for cooling, cant afford a cooler. But my shrimplets seems to be doing fine, still be able to see them around.

Did a water test yesterday, PH at 7.2, ammonia & nitrite is near zero. Only my Nitrate and Hardness is slightly high. Will this affect my shrimps?

I remember the last time I tested, about 1 month ago, the Nitrate is same as now, but the water hardness did went up. Any way to reduce the Nitrate and hardness?

I have about 15 adult shrimps, some shrimplets, 2 otos, and mainly mosses.

I top up water daily using the water from my other tank (1.5ft)with fishes, the water parameters in the same tank is close, the nitrate and hardness are not high.

Pls advice. Thanks.