Welcome to Tropical Fish Keeping forum, nags and NeonTetra2196.
I'm copying over a post I made yesterday in another thread on the issue of water changes, as this may put things in perspective. I will expand on this in an article i am working on concerning water changes, but for now this should help.
Water changes are the most important aspect of tank maintenance. You can let the fish go without feeding for a couple of weeks and it will not harm them. But you cannot fore-go water changes.
"Stuff" that I have often termed "crud" accumulates in any tank with fish, and the only way to remove it is with a water change. Plants can handle some of this, in time, and if not overwhelmed. But at the level of stocking most of us have, a weekly water change of half the tank is necessary. This crud is urine (about 30% of the fish's body mass is excreted as urine every day), pheromones, dissolved waste, bio-filtration end products and other pollution. TDS (total dissolved solids) build up quickly; these come from the water conditioner we have to use, from fish foods, from any medications, and from just about any substance entering the water. None of these substances can be removed by filters...only with a water change. And these substances affect fish big-time.
The other aspect is water stability. The larger and more frequent the water changes, the more stable will be the water. Now, this assumes we are relatively close in GH and pH and temperature. These are relatively easy to control--another reason for selecting fish that match your water parameters. They will be healthier than fish that do not match, either because of stress from inappropriate parameters or from stress caused by using chemicals with TDS to adjust the chemistry. Any biologist/ichthyologist will tell you this. The more water you change, the more stable the chemistry will be, and this is crucial for fish.
Jack Wattley is an acknowledged authority on Discus
, having bred and raised them for most of his nearly 80 years. In almost every one of his monthly TFH columns he mentions the necessity of water changes, pointing out that in his tanks he performs 90% water changes every day. There are hatcheries in SE Asia that perform 3 and 4 such changes every day. With respect to the water stability and health of the fish, you simply cannot overdo water changes. As for those who say water changes stress fish, the more you do the more accustomed they will be to the commotion, and even come to enjoy it. I've had fish nibbling the hairs on my arm when I've been in the tank trimming plants. And a siphon sticking in one end pulling out water or adding fresh water is not going to stress fish.