Any ideas?

A huge strelitzia, an eight foot tree aloe and a multitude of smaller aloes are all gradually dying off.

We have ruled out over watering and contamination from chlorine from the pool water. There seems to be nothing wrong with the soil after we took a sample to a local Centre for testing.

We now need to a specialist to come in and have a look. I will be so sad if stuff can’t be saved :-(