Lol B.
I've just been reading a thread where you posted that you just top a tank off. I know this is a different case but you have a hand in both clubs
I must have been unclear in that other thread, I pretty much never top a tank off. My betta tank evaporates more and I add distilled water if I add anything. It gets a 50% water change every week with a few smaller changes in between and I test it every few days. I don't top off the 29, it never needs it.
Maybe you read how I do a simple, passive water change occasionally with a slow drip from aquarium tubing. That's not my weekly big maintenance routine, it's something I do a few times a week for more changes. And yes I understand five changes of 10% isn't the same as one 50%.
My 29 gallon has been at about 2-3 ppm nitrates and dropping, and I do have live plants.
I'm just curious what people use as their hard and fast indicator ... A schedule or water tests.
Yesterday I took samples to LFS, one tap and one "dirty" tank water (due for a water change). He tested the dirty tank water then said "ok now let's tests the dirty water". I explained my approach to water quality and got a lot of compliments.
If I go by my nitrates, aqua advisors suggestion is working. If I were to do 50% a week I'd have no nitrates.
I'm not trying to be lazy I'm trying to understand what's best for my animals. My tap water is practically distilled, I'm using coral for buffering capacity because I get wild swings with other buffers, and 50% a week creates greater fluctuations in KH and pH. If my fish really need that much of a water change, it's iust as much trouble as a 20%. I'm just balancing all the variables. Given what I add to the water for GH and KH, consistency with TDS is important.
I also asked to get a general range of opinions that's useful for lots of people. 50% a week is a great rule but too little for some people and too much for others. Nitrates at 5-10, and good stable number on all other parameters, is a little less one size fits all.