Best substrate for AC ant tower?

[nikkirichards03]

I have a small colony of ghost ants (tapinoma melanocephalum). They didn't like the sand that the ant tower came with as they're really tiny and the sand is almost as big as them. I switched it out for coconut fiber, which is what they were living in before, but I'm having a problem with it constantly molding from the moisture in the tower. Is there a similar, lightweight substrate that won't mold up as easily from the tower's bottom up watering system?

[antnest8]

Maybe potting soil, It will still mold but maybe not as easily.

[Ikerrilove]

Maybe you could get some springtails to add to it?

[Hunter36o]

I use Coco fiber and a potting soil mix from my local garden centre and I have them in a 50-50 ratio. I use it for my ants, stick insect, darkling beetles colony and my sling and I never have mold issues. I actually had a mold outbreak in my beetle enclosure bit it's was strictly on the oat meal that got pushed to the beetles apple. It did not spread all over the substrate. You could try that.

Oh it is an indoor potting mix if that helps.