Hello emerald. Water changes need to be done for the specific reason that oxygen in the air depletes nutrients from standing water. Without going into the chemistry end of things, think about why a glass of water straight out of the faucet tastes much better than a glass of water that sits out on the counter overnight. Fish do all their business in their closed environment. It's essentially a toilet. If you were doing that in your water, how much and how often would you like it changed??? The more water you change and the more often you change it, the healthier your fish will be.
10 Tanks
There are many ways to keep tanks healthy and going... So, if something works for you, it simply works for you...
I do know why a water change is needed. For I'm keeping myself busy with fishtanks and fish for almost 50 years now. But it's just the frequency you're doing the water change and the amount of each water change that sounds too much to my ears. And I know what I'm doing overhere. It's also a bit different to fish in comparison to humans when it comes to the bioload in water. A tank that has the chance to settle when it comes to the water culture needs its time. To do a water change that fast and so much doesn't make those fish healthier or even stronger. What you're doing is just to keep the chance on a sickness to a low level by those frequent water changes. Nothing more. But that doesn't mean that they're healthier or stronger. It's more that fish that are kept in water that does have a certain level of bioload become stronger than those kept in only clean water. And this is experience that is talking to you.
It's even better when water has got some color than a total clear tank, tbh. Seasoned keepers who are in the serious fishkeeping would agree with me.
I even had two tanks that didn't had any heaters nor a filter. I've kept those for like 3 years without any problems. I only added water when some water had evaporated. It's just that at some point I needed those tanks for a different purpose but otherwise I would've kept them the way they were. Fish stayed healthy and they reproduced in a good pace.
But this is not attacking you, btw. To repeat myself: If it works for you, it works for you...
But if I read on several forums how often people have problems in their tanks by sticking to what they've read at a serious number of relevant internet sites, it make me curious why I hardly have those problems all these past decades. I'm very old school. I'm probably also a lot older than you. But how we maintained tanks back in the 1970's and the following years, there weren't that many complaints about tank and fish issues. I'm still sticking to what I've learned back then and that works for me perfectly. A water change overhere happens once till twice a month and I can assure you that the water parameters are fine. Only during the summer season, I fill those tanks extra because during that season the water evaporates faster. I don't even use heaters in none of those tanks. I work with the circulated air in the fish room and the ones that need higher temperatures are kept on higher shelfs and those that prefer lower temperatures are kept on lower shelfs. It's a normal thing that warmth goes upwards.
Please, feel free to way in if you want to...
