First of all good for you testing your setup before putting any creatures in there.
You do have some more things to think about and get tweaked before putting any uros in there.
Here are my thoughts on what to look at (not the only way to do things just what I would do)...
First of all I believe you said you were getting a pair of U. Geyri. If you are only getting one then ignore this part on pairing issues. If you are getting a pair they should be quarantined until they both get a clean bill of health from the vet. I know they are probably both coming from the same breeder but that still doesn't mean one can't have a sickness the other doesn't. You could keep one in a 50 gal plastic tub until they are checked out. Even if keeping them seperate for health reasons weren't enough you need to be ready to house them seperately in case one becomes aggressive to the other. Again even if they lived together at the breeder a major change like this could set off aggressive behaviors. Also that appears to be 50 gal tank which will be very tight for a pair. As Torey pointed out tight fitting hides are important for the health of a uro and you will need twice as many of them for two. Also you should have at least two basking spots and two feeding areas just in case they don't like basking/feeding together.
In addition to the tight hides and access to the basking area pointed out by Torey and Elizabeth you may want to consider removing that concrete block as it may contain things you don't want your uros in contact with. There was a post quite some time ago that someone had tested a concrete patio block positive for lead. Now I doubt that most concrete products have lead in them but I don't think there are any safety and testing requirements for products like that. Who knows what may have slipped into the concrete mix. You shouldn't have any problems using things like ceramic tiles or other home products meant for indoor human use as they do need to be tested for lead and other contaminents.
Getting things setup and tweaked right for the first time can be a daunting task and you have an uphill battle with a pair in a 50. If you don't have them you should pick up a remote probe indoor outdoor thermometer and an infrared temp gun as it makes testing and setup a lot easier (at least in my opinion)
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Mike Wilson
mwilson@fuu.net