Reeve's? Good choice!
I have four reeves at home and they are among my favorite turtles. They are smart, personable, and easy to manage. I think they are very neglected on people's "cool turtle" lists.
You will find, that if you start with a healthy specimen they will put up with a lot without illness (not that you would mistreat the animal, but should it's conditions be sub-optimal for a while it will not easily sicken); they are quite hardy.
I do think though, that a thirty gallon is too small for an adult reeves. If you buy a hatchling, it will be find in such a tank until it is about 3 - 4 inches long at which time you should roughly double the size of the enclosure.
Reeves seem to do well when treated as a semi-terrestrail (like a wood turtle or some Rhinoclemmys species).
To wit, you should devote about 1/3 to 1/2 of its cage for land and 1/2 to 2/3 for water.
My recomendation....to get the most out of your space is get a huge amount of large smooth gravel along the entire bottom. Use "river rock" or similarly sized (pieces at least the size of a quarter) smooth stones and pile them up almost halfway up the tank. Then get a large plastic (rubbermaid or sterilite type) shoe box or sweater box. Find one about 1/3 to half the size of the tank's bottom. Fill this with clean topsoil or terrarium soil (make sure you get one with no styrofoam, perlite, or fertilizers of any kind)
You can the sink some plants with or without pots into the
soil-filled box if you like. Place a small hide log or make a cave in this box as well. Pile the stones really high and sink the box in.
Then fill the ramining space with as much water as there is room for without sokaing the box. If you are careful you should be able to get 6-12 inches of water this way.
Reeves are good swimmers os this will not be a problem.
If you like you could support the box even higher on bricks or flat rocks so that the turtle coulsd swim under it.
I would then invest in a siphon or some device to drain water and a good power filter.
Get maybe a Hagen aquaclear 500 powerfilter. Or the biggest Penn Plax Cascade power filter you can find. (much cheaper on internet)
You might also consider putting in an undergravel filter beneath all the gravel and getting some powerheads with a reverse flow kit to operate them (Marineland's Penguin line has these and they are of decent quality)
If you have a long strip fixture get a Zoomed reptisun 5.0 UVB light (also sold as "iguana light"
or Esu's Reptiglo 8.0
You will then need a basking bulb also. Any 100 -150 watt light bulb will do.
If you do not have a strip fixture, then consider getting a mercury vapor bulb for heat and UVB. There are several kinds all seem to produce similar amount of heat and UV You will want a fixture which is made of ceramic and not plastic for this. Youi may ask others for opinions on these as I do not use them.
A good screen top for ther cage will help positioning of the lights.
You may wish to consider darkening several sides of the tank to help the animal feel secure. Aquarium backgrounds or paint are useful for this.
If you have snakes then you probably know about thermometers. Get a good one you like and check temps. I keep Reev's water at about 72 - 76 Air at about 75- 80 and a fairly cool basking spot temp of about 87.
As far as feeding goes,
Reeves love worms of all kinds: red wigglers, earthworms, nightcrawlers
Wax worms and superworms will also be taken.
Crickets are good as well but dust all insects with a calcium powder.
Some fruit and greens can be offered (berries are a good choice as are figs) I have had some Reeves eat Swiss Chard and Collard greens but they have avoided others. Mushrooms and strawberries go over big and are easy to sneek small amounts of chopoped greens, slivered carrot, and smashed squash into for extra nutrition.
A decent pelleted food or two is good as well. Get Mazuri's Aquatic Turtle Diet and maybe Hikari's Sinking Algae Aafers and sinking Carnivore Wafers.
I have seen one Reeve's (not mine) eat duckweed and salvinia but mine never touched water plants.
I hope this helps some.
