running your lights 24/7 prevent the caulerpa from going sexual, because they are not able to produce gametophyte plants. All plants and algae have two different lifecycles, a sporophyte and a gametophyte stage. The gametophye stage produces male and female gametes, that when released, can combine and form new gametophyte plants. This is the sexual phase that most are referring to. This phase requires darkness to form, and by keeping the lights on 24/7 the plants never grow sporophyte,and thus all you reproduction is asexual. Asexual just means that the plant cells divide mitotically, and never in fact produce male and female gametes (egg and sperm), therefore you just have a bunch of clones in the fuge!
HTH, good luck
jon