i have some of that sponge its bright yellow and everyone always ask what it is and i simply say thats sponge bob square pants.
on to your question i have a 50gl was running 2 years then i bought it moved it in a day and has been in the spot it is now for almost 5 years, quick specs on tank are 50gl no sump hang on skimmer only lots of flow good amount live rock no more then 2cm thick sand bed 400 watt mh
so the tank orignally had a queen skimmer ran that for 2 years then had a reef club meeting decided the skimmer was to ugly and got a dymax mini skimmer never skimmed more then 4 tea spoons of skimmate pathetic, so i switched it of and left it in the tank (corals are growing off it) over the course of the next year the tank had no skimmer and very few water changes maybe once every 8 week, i use amino acids and trace elements by koralin and aquavitro for ca kh and mg and at that time i had the best colouration of my acros ever but i wasnt getting much polyp extension so i hooked up a big skimmer to it to try and fix the problem, what does this have to do with sponges u might ask, well as i said i have that yellow sponge pictured above while i was not skimming it grew and grew and grew to the size of a fist, 5 days in to skimming the tank it shrank and disolved to the size of a thumb now its found a happy medium. i would love a cryptic tank as sponges are nice to look at would probly have mussels in the sponge tank to
i am not the biggest advocate of skimming whil i do think it good i do not think it a necessity to skim all the time, unless u have a lot of fish and need the oxygen all the time to sustaine O2 levels
