the turbos will breed in your tank. As they have direct develoopment (no planktonic stage) their numbers can build up. The strombs will breed (as long as you have male and female strombs as the sexes are seperate in this species) but there is a planktonic stage which will not survive in the average aquarium. I have a 700L tank and I have 3 strombs (2 females and a male), three Trochus and 6 turbos. Between them, there is no algae left. In addition to the snails that I have added, there is a host of other algae eating mollusks, including several juvenile Abalonies (I also have stromella which looks like a minature abalone with a long tail). Before you purchase additonal "algae eaters" it may be wise to see what beneficial hitch-hikers arrive on your live rock.