How often should i change the substraight?

[Sublime]

When it starts to smell, dirt gets too wet (soaked), or as a safe route - change every 1-2 months.

[cyris69]

I second the when it smells. Once it looses its coco-fiber smell and gets a bit sour its time to change it. You have a large enough tank to build a viv and let it become self-sustaining

[toxxxickitten]

I would change it once a month and spot clean otherwise.

[Beardo]

Ditto what the others said....also, I have that exact same shelf unit in my room, lol.

[GRABibus]

I change the substrate locally when for example the frog stayed at the same place during some days or made poops at this place.
Otherwise, I change it every month or 2 months.

The greater the enclosure size, the longer you can wait for changes.

[Mikey]

I've changed my substrate twice in 2 years. never had a problem. My frogs only poop in there water. that gets changed daily