Yes, you have to take care of your ecosystem, but only about once a year.
When the leaves touch the glass its time to give them a little trim. After you trim the leaves and twigs, you need to leave the container open for about 72hrs so it can heal.
If possible, combine the pruning and watering - it'll save you some time!
The plant, the "tree" in the center of the jar is betweem 2 to 5 years old and only need a "trim" once a year. If it shoot long sprouts the ecosystem is to far away from the sunligt.
Move it closer to sunlight.
All plants and moss will need a bit of a trim once a year. Keep an eye on how it grows. When leafs touch the glass, cut them off. Leave the jar open for 48 hours after trimming.
Your ecosystem will need sunlight, not to much, and not to little - just like Goldilocks! Place the ecosystem about 3ft from a window, or anywhere it'll get enough sun. Pay attention to your plants, and they'll let you know what they need! If the jar continually has condensation, that's a sign it's getting to much sun and is too warm - if the vegetation is sending sprouts - it's too dark, so adjust the placement until you get the balance just right!
Keep an eye of your ecosystem the first month. If its to much sunlight or to warm there will build up a lots of waterdrops on the inside of the jar. There should always be a little bit of drops, but not too much.
If the plants are sending out sprouts and are "reaching out" for sunlight it´s to dark for it, move it closer to the sun. During winter - place the ecosystem closer to sunlight, or add a flower lamp nearby.
Your ecosystem will only need water 1-3 times a year, depending on size. A medium/large size may only need to be watered once a year.
Just use the "mist" setting on your water bottle, and give it three sprays on the inside wall of the jar, then put the lid back on. That´s it!
Did you give your ecosystem to much water? Dont worry, unless you drowned it in three gallons of water, it'll be fine - just open the lid and let it "breathe" for a couple days and then replace the lid. Keep an eye on the ecosystem for the next three weeks to make sure its doing well.
When do i water it?
An easy way to see that your ecosystem needs water is to look at the moss. Does it looks dry? Give it some water. The leaves, do they look dry or have brown edges? Give it some water.