I have it for a 6.5 months, the sponge was practically dead in 5.5 months (still few orange spots then, but not now). Polyps still alive.
1. Direct conthact with aiptasia and treating aiptasia by kalwasser could contribute to its decline
2. Too mach particulate organic matter in the tank (almost continuous feeding for non-photosynthetic corals, detritus and shedding LR).
3. Too strong flow, eventually breaking contact with the base (medium for everyone else in the tank).
4. Feeding sun corals by grocery seafood blend, if you check the plastic glass where this food was - it has some palpable residue. Later tank developed transparent, likely bacterial, film and red cyano. Switched back to mysis.
Some hitchhiking sponges in the tank are doing very well during the same time, piece of the spiny orange sponge in the sump too.
Food for the 90g tank, low light (110W PC, sponge was 24" below):
- Fish was fed 3x daily, quarter of cube total each time, mix of mysis, Marine Cuisine, Reef Plankton. 1-2 Formula Two pellets for a blood shrimp once a day.
- Food for sun corals, total 7-8 cubes equivalent for each feeding if fed twice a week (less, if more frequently). Mysis, Plankton (zoo, larger, than mysis), some Marine Cuisine, grocery seafood blend.
- Food for NPS gorgonians and snack for planktivores: dried Cyclop-eeze, decapsulated brine shrimp eggs and ZoPlan minimum 5x a day, when I have it - frozen Reef Plankton, rotifers, baby brine.
- Food for scleros, dendro and Muricella plectana: except sleep hours, they are fed every 1.5 hrs, food content changes as I try new varieties: Hikari First Bites (powdered fry food), ESV dried phytoplankton, later - concentrated algae Nannocloropsis, live rotifer culture (super small SS-strain) once in 2 days, for a short time: RotiFeast, Shellfish Diet(this continues now in a very small doses), Brigtwell phytoplankton 8-30 um, DT Premium Reef Blend, Weiss Reef bugs and Spectra Vital.
No live phytoplankton (have no possibility to sterilize and general lack of space and time), it could be the key, together with water, low in particulates content (could clog the sponge's pores).
Post your results, when you will have them, and your thoughts on what contributes to its life or decline, and what else could be tried, please.