I love my sponges. Some of them are very pretty...especially the yellow and orange ones. I have several that are dark blue or white. Those aren't as pretty but still interesting.
Do you dose silicates? I acquired mine due to dosing silicates to help combat dinos.
Only slightly off topic, for people with out of control sponges, have you ever tried nudibranchs? I have a good deal of them as well and enjoy them. But if they were to get out of control, was thinking that a sponge-eating type would be cool. I love nudis and to have them coexist would be nice.