humidity and mold


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Well-known member
Sep 4, 2016
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Maryland, USA
How do you keep humidity high and no mold? I have a small 2 gallon terrarium with almost an inch of coconut fiber and I had some moss in it and the moss molded. So I took the moss out. I also saw some mold on the coconut fiber where the moss was. Now I am worried there still may be mold in the tank. I have taken the mantis out for now.

I can't seem to keep the humidity up without mold forming. How do you keep mold away if the humidity is high?

I have never kept a high humidity species as a disclaimer. But first I would get rid off ALL the substrate and replace it with new guaranteed clean substrate. As for preventing mold in the future, maybe putting in some springtails and isopods? They help control mold droppings and more, commonly called a “cleaning crew” though you may have wanna put a little plant in to keep them happy. Which would also help keep humidity high!

Also give the tank it’s self and all decorations in it a good thorough cleaning

A great way, as @Skcib said, are springtails and possibly isopods. Isopods can be harmful to your pet and have been known to “nibble” on pets. Isopods will also only pay attention to poop. They won’t eat mold. That would be up to springtails. A VERY good way to keep substrate from molding would be cross ventilation as it would keep air flowing. Mold loves warm, moist, stale air. What pet will be in the tank?

Personally I like to keep moist moss in a seperate container and culture springtails. I use this mixture on top of 1/4 to 1/2 inch of vermiculite works great for adding moisture and easy to monitor. Also vermiculite is not organic so nothing to cause mold and it's lightweight. The main thing is to understand why to increase humidity on some species. For the most part the main time to have higher humidity is at molt the higher humidity helps slow drying time so mantis has more time to exit exoskeleton. I find even more important than humidity is just keep mantid hydrated food and water to drink for most mantids even though some get hydration from food mainly. If you you keep out mold and add live plants that increase oxygen you can have higher humidity with little bad effects. Also depends on how you obtain the humidity if you get humidity by shutting of ventalation then you can get issues real quick best is to have more ventalation  and add a way to add more moisture or to retain the moisture. Thiss is why I like the vermiculite and moss the vermiculite wicks moisture and a thicker layer of moss slowes the evaporation rate of the water then the springtails eat organic matter that causes the mold. This setup works great for my orchids. 

Thanks so much for all the replies everyone!

I do have a container of isopods but I don't like to put them with my mantises. Not to mention since I can't seem to keep humidity up they would not survive in the container. I do not have any springtails at the moment and it is a little cold outside now so I am not sure I could find any now. Where do you get vermiculite?

The tank was for my female Grizzled mantis. But since there was mold in there I took her out. I can't put any more ventilation in the container since it is acrylic walls. So maybe that tank just can't have moss with coconut fiber. Its like either it is super dry and can't keep humidity up or there is mold.

The container has been dried out and I will put new coconut fiber in it if I decide to set the tank up again.


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