can anyone help?

[mollypolly]

Hi, I was wondering if anyone can give me any advice. I am new to shrimp keeping and finally thought that I had sorted out how to keep them but two days ago I changed a third of the water as usual . I also removed the green algae off the sides of the tank with paper towel. I also placed a new plant in, some java moss, which a lot floated to the top. I had soaked this for a few days in a bowl of the tank water. A while later I noticed the shrimp were all hanging onto things right at the top of the tank. i checked the temperature and it had gone up to 26-28. over the next hour 6 of my shrimp died and one died yesterday. i only have four left now. they seem ok at the moment. Does anyone have any advice on what went wrong and what I can do to make sure it happens again. I feel awful about it.
Any advice gratefully accepted.
Mollypolly.

[mithrius]

did u have a heater on?
i know my tank in my office here use to flucuate alot in the lower temperatures..
i got a very small heater (hydor) and this helped to stabalize it and now it only fluctuate a few degrees when i turn the lamp on or off.