You need to get them separated ASAP. Never in pairs. Also can you get them on orchid bark or fir bark and each in its own much bigger enclosure. That is quite sad how small that enclosure looks and two in it.
That food also is not suitable. Get them some orchard grass hay, cactus pads...
Yeah I couldn't tell for sure if that was getting filter uvb or not.
Pothos, Boston ferns, hibiscus, grape, hosta to name a few that you could try planting.
It looks very nice.
However, tortoises should not be housed in pairs
Uvb will not go thru glass and is almost all block when going thru fine mesh screen
Temps should be held between 80-86, around 84-86 being best.
I see no heat or lights.
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If you get a hatchling, it needs to be housed indoors in a closed chamber high humidity enclosure for approximately 3 years. During those three years or so it can have short visits outside
Once it's big enough then it can live outside in a safe enclosure. Do not let it roam the yard...
For the occasional sneeze and bubbles, you can play it safe and bump up the night temps to 75-80 for a while and see if that takes care of it
Can't really see anything with the poop liquid. Possibly parasites. Take a stool sample in to a reptile vet. Call them first if you don't already have...
A sulcata should never be kept in temps under 80 as a young one.
You need to get that night temp up ASAP or you will have a sick tortoise on your hands.