First-Time Tropical Terrarium Set-Up for Cattleyas

[galguibra]

I've been growing some mounted Cattleya seedlings (intermedia and aclandiae), and I'm looking to put them in a bioactive terrarium. I went with a 12"×12"×18" Exo Terra to have some room for potential future additions, and I was hoping to get some advice on maintaining good conditions in the tank/a general sanity check on my plan for the set-up. I haven't actually put anything together yet and I've held off on buying any other live components until after I've finalized the actual terrarium, so everything is still adjustable if you have any suggestions!

I'm planning on putting in a 3" LECA drainage layer, and then a 3" layer of ABG mix for the substrate in case I decide to add any terrestrials down the line. I got some terrarium mesh to keep that all separate, and I'll be adding springtails as a clean-up crew along with some beneficial microbes. The two Cattleyas will be mounted on cork bark, and rather than adding leaf litter (I just don't really like the way it looks!), I was planning on using live moss.

For climate control, I have a thermometer-controlled heat mat and an ultrasonic fogger with a sensor probe that lets you set upper and lower bounds on RH and VPD. I also have a 30W grow light and an adjustable dome ready to go for lighting, and I'm shooting for around 300 PPFD on a 14h/10h cycle for a DLI of about 15. Both intermedia and aclandiae are warm-growing, so I figured something in the mid 70s to maybe 80°F should be fine, but I wasn't totally sure on where to set it. As far as the humidity, I was planning on maybe 65% on the low end to 75% on the high end, but I'd be interested to hear thoughts on that since I don't wanna push my luck with mold/rot.

As far as air circulation, the tank has a screen top and mesh ventilation holes along the front just under the door, which they say are supposed to create natural upward airflow and prevent condensation. I'm not sure if a fan is required or not, but I also have some silicone mats I can cut to size and use to partially cover the screen top if necessary to keep the humidity up. I was also planning on taking the orchids out maybe once a week or so for a good fertilizer soak since I figured I should minimize runoff in a closed system, so would that be enough to keep things suitably fresh in there? I'm not planning on adding any misters to keep things relatively simple/affordable, so there wouldn't be any additional water in the system besides whatever comes from the fogger.

[estación seca]

That all sounds good. The humidity might run higher than you want, in which case a fan might help. You might not need the fogger. They will quickly outgrow that terrarium if they're happy.

[galguibra]

Originally Posted by estación seca

That all sounds good. The humidity might run higher than you want, in which case a fan might help. You might not need the fogger. They will quickly outgrow that terrarium if they're happy.

Thanks for weighing in! What humidity range would you recommend for those species though I had seen in a few places that aclandiae prefers something like 80%, but I figured that would be too high for the intermedia and invite mold growth. My apartment is dry enough that they both fully dry within a few hours of their daily soak (part of why I wanted to put them in a terrarium to begin with), so I was hoping the fogger would buy me enough passive moisture that I could leave them alone for most of the week and not have to worry about arranging a plantsitter/automated mister/etc while spending the occasional few days away from home. It'll turn off by itself once it reaches the upper set point and not turn back on until it falls below the lower one, so if there's an average you'd recommend then I could set it around that point

I imagine the aclandiae will probably have enough space for a good long time as a miniature, but I agree yeah that the intermedia is likely to outgrow the enclosure after a few years. They're both still multiple years from blooming size, though, so I'm not toooo worried about space for now unless I start wanting to add more plants

[estación seca]

65%-70% is good.

[Roberta]

Remember, too, that humidity varies over the diurnal cycle. In a natural environment, it will be higher at night when it is cooler. So if you let that natural process operate, so that the plants have a chance to dry out during the day, experiencing a cooler, damper night, I think that you greatly improve the chance of not running into fungal issues.