As for your 23g sump..you should be okay. Whats the bioload (how many fishes)?
As long as the load is not maxed out ..it should be able to handle it with no problems. Just make sure you have a large enough space to pack in a lot of bio-media..whether its scrubbies, balls, ceramics..etc, and have a sufficient amount of contact time with the water.
What are the size of the overflow and returns?
try to go as big as you can... yeah its ok to use a 23 gallon but a 50 would be way better..maybe even a 6o.. and you can split and have a grow out tank on one side.... but bigger is better... the 23 is pretty much minimal
If you consider the available volume of the 23g and the available volume of any hob or canister, you will see that it is way bigger than any manufacturer thinks you need.