How hardy..............

HI, Just wondered how hardy these guys are if all the parameters are ok, at the moment  I do a wc once a week, do they need any special care........

Which guys? and what do you mean by hardy?

Domestic Angels, ie captive bred fish from captive bred parents are generally pretty tolerant of a wide range of water conditions, by contrast wild caught altums have very specific requirements.
In a typical community setting weekly water changes are perfectly adequate, but if you're trying to breed them, when raising large numbers of youngsters regular feeding and more frequent water changes are required.

If by hardy, you mean forgiving of less than ideal water quality in terms of ammonia, nitrite, nitrates, etc. It's probably fair to say that domestic angels will survive in water that would probably kill many other species, but there's a big difference between "survive" and "thrive". The better the water quality you provide, the better the specimens you will raise in the long term.

Sorry I should have been more specific, but you answered it for me, I never have ammonia, nitrite, nitrates, I was more concerned about tank water being soft, I went to wharf today and spoke to the angel expert, and he said, most are tank bred and are used to wider parameters to wild, just as you have said, many thanks for your reply