It doesn't seem like the appropriate heater for a 24 nano. Unless you've rigged up an outboard filter... canister, sump.. something where you have tubing running through the open air, you can't use one. The JBJ 24 has all the return tubing submerged. I'd go with a regular submersible glass heater. I use a Jager 50w on my JBJ 12. You'd probabby need a larger one though.