It's always a good time to look at the sub and think about how we do things. One discussion is always how to change the sub. Do we have to remove it and totally rebuild the tank?
We all have differing opinions and that is very important first step but I would like to throw some light from my view. I well know the problem of getting the sub wrong and still not wanting to blow it all up and start over, but I've found a way to work around that problem. Step one was to look at what I really was wanting and I found there was no need for a solid one color, one type sub as it was not what looked right for the waters I usually see. I'm a freshwater guy and rarely look at the ocean beach as what my mind thinks of as "natural".
So how to change without blowing it all up to start over?
Let me share what I do and then see if it fits for your use.
No matter what sub I have in a tank, if I want to change, I do not remove it all ---too much setback and too much work! But if it is too dark I add light colors or too dark, I add light colored. If I want dirt, I put it somewhere and cover it with whatever is the sub of the moment.
So how to add sand,dirt or gravel, etc. without killing the tank?
I look at what amount of adding I may want to do and choose a soda bottle that seems right,( one liter, two liter?) cut the bottom off and use it as a "transfer" vehicle. Lower the water level to make it easier, cut the bottom off the bottle and leave the cap semi-loose for easy removal. Then when the bottle is loaded with the new stuff, I ease it down into the tank where I use one finger to slip the cap off as I press the bottle into the existing sub. Then as I keep the bottle near the bottom, I move it around , up and down, to spread the new out without too much of a dust storm. Smooth and shape it as needed and wait
I do this in a small section at a time and wait in between loads to allow for the bacteria to recover from the portion killed in the change and to let the filter clear any dust that I do make.
As far as the plants, they don't seem to care very much as long as I keep the leaves clean and it certainly does make my life more fun when I give myself the freedom to pick and choose what I want, not be the puppet of what the tank wants!