I have an indoor fountain that is made of copper. I would like to inhibit bateria and algae growth in the water, but don’t want to corrode the copper (or the ABS pump or PVC fittings). Does anyone have any suggestions?

I am using an old milk can as a water fountain and want it to look like milk is spilling out of the can continuously, but the substance used to color the water can not be thick to clog a circulation pump and it needs to be non-toxic incase the children get into it becouse it will be at ground level.