Aquarists, by nature, are inquisitive people. Cichlid keepers probably more so. Nearly every cichlid keeper has experienced the "must have more" syndrome or fever. You know what I'm talking about. You get your first tank set up with just a couple of cichlids and very soon you want more....both tanks and cichlids.
As you feed your seemingly insatiable desire to have more fish, you begin to branch out with respect to your aquarist toolkit. You began with a HOB filter and now you want to get a canister filter or even a trickle (sump) filter. You're attached to one brand but now you want to try another. The list goes on because there are now so many options for heaters, filters, filter media, etc. The supplies available to you are now only limited by your budget.
Herein often lies the problem. As you gain more experience and begin to expand your operation, you branch out into trying new things. This results in fish keeping becoming a grand experiment. From a water parameter perspective, it's hard to tell if that switch you made in bio-media is really making a difference, especially if your tank is mature and your ammonia, nitrites, and phosphates are zero (the former two should always be but the latter may not, depending on the type of biotope you're attempting to emulate). Occasionally, you can add media to your filter that you've never used before and be able to tell a visual difference in the water, especially with water clarifying media. If you're really experienced, you can sometimes tell a difference in the behavior/appearance of your fish based on filtration or media changes. However, most often you can't tell.
Experimenting can be fun and I encourage you to do so, but remember even subtle chemical changes that you can't visually see or that are exposed during water tests are certainly noticeable to your fish. Many chemical reactions are always taking place that you are incapable of seeing with the naked eye. Be judicious about how you experiment. Trial and error is a good thing....until you lose fish because of it.
The Cichlid Room Companion
Tropical Fish Hobbyist
American Cichlid Assoc.
African Cichlid Hub