Thanks for the help - I will proceed with the tap water just in case I have leaks - I'm not completely confident of my plumbing skills - I installed a new bathtub in the ensuite four years ago and flooded the family room

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Deborah and I also want to take our time with the aquascaping and intall a solid foundation of dry rock. Hence a second reason to go with the first fill of tap water.
Thanks for the help.