5 gallon fish tank with 5 white clouds and 3 guppies you change water 20 percent per day is this ok?

No. This is overcrowded and you change the water every day? That will stress the fish out and the constant change of chemicals and temperature can harm the fish. Please do not continue this. When a few die do not get more. I suggest change the water once every 1-2 weeks. Whatever you do, do not continue this.

You should consider getting at least a 20 gallon tank, or re-homing some of the fish to avoid overcrowding your fish.