Albino Bullfrog

I just purchased a three inch albino bullfrog, a beautiful amphibian. I have it in a 30 gallon terrarium (50-50 terrestrial/aquatic) with a filter and airstone. It is sharing it with two six inch tiger salamanders, and a six inch mud puppy. They seem to be doing well together. When the bullfrog gets bigger, I know he'll need his own enclosure. But for now, anyone foresee any problems?

When the bullfrog sees me, he jumps and hides underwater. But he doesn't seem to mind the presence of the other amphibians.

When mixing amphibians, there's always the risk of disease. Another thing I would be worried about is the mudpuppy. From what I understand, they need pretty powerful filtration (to create some sort of current, since they live in rivers) and cooler temps, somewhere in the 50-55* range. They also require somewhat more room than a 30 gallon tank can provide, especially if the tank is partially terrestrial, as I'm assuming it is.

The mud puppy is eating, the water is aerated with an air stone, and the water is filtered 24/7. I'm not sure if the mud puppy is happy, but he seems to be doing fine.

The terrarium is half land. The tiger salamanders spend 60% on their time on land. The mud puppy and newt spend 100% of their time in the water. The bullfrog spends all night on land, and when the light comes on in the morning, jumps into the water, where it spend all day.

They all seem to ignore each other. I have not yet seen the bullfrog eat, but I think she eats at night.