You can grow them out for a while in the 55, but you will need something bigger down the line, especially if your JDs form a breeding pair. The breeding pair will be rough on the GT in that size tank. Save your money while they grow out in the 55 so you can get a bigger tank later. Check Craigslist, you can find great deals. My buddy just called me about a local listing on Craigslist for a 150 gallon full set up, wet dry included, for $350! There's no need for you to go that big though. I was just giving an example. Best of luck to you!