Thanks,
@jaypeecee. Actually, I meant to mention the PH issue the other day when talking about water hardness (or softness being the more appropriate term!) but was being called away and forgot to resume that rushed post. Oddly, the PH here is actually alkaline (almost 8, according to the water company!) - but, from recollection, it used to be acidic ~10 years ago. I'm wondering if something is now added to the water to enable that and prevent PH drops, given how soft the water is. It seems to be the same for various postcodes around the country. The website does state "The pH level in your water supply must be controlled so it doesn’t corrode the metal distribution pipes by being too acidic, or leave deposits on the pipes if it’s too alkaline." My strip-based test kit always gives an acidic reading (an error or picking up something about the 'natural' PH..?!), while the liquid-based test kits have always given a reading consistent with the water quality report, including after standing for ~24hrs.
(1) Total carbon is around 1.3 - does that help?
(2) Not in past 5 years, but I did have trouble fishless cycling (albeit with fish food method). However, in the past when much less knowledgeable, I'm almost certain I had PH crashes as PH was around 6 at some stages albeit I only tested very occasionally, usually when there were tank problems.
(3) Hopefully this is circumvented by whatever is being added to increase the PH.