My normal regime is a c50% change every two weeks. However …
… I have just, coincidentally, finished a period of heroic restraint during which I did nothing to my tank (except add food) for seven weeks. I wanted to see what would happen.
I’ll be writing up the results in due course. I’ll be posting them in the general fishkeeping forum that I inhabit, from whose Members there’s been some interest because of the Paros’ (relatively) extreme conditions. I’ll post a link in this thread when I’ve done it in case they’re of interest to anyone here and hoping that you may offer some helpful criticism . It’ll be some time yet, because I want to try to establish the reasons for one or two of the results ; and I’m going to wait until the tank has been well-settled at its former parameters before repeating both a dip-slide test and an assessment of where some micro-organisms seem to be concentrated.