Let me know how to get these sponges? I have been researching and it looks like most of the live rock places don't do that anymore....View attachment 32386778
Often sand will get a thin layer of some kind of nuisance algae on it. Stirring the sand will hide it some but often as it propagates it can get pretty annoying for some. Instead of disturbing most of the sand bed and biology just siphoning off the thin top layer and cleaning it as mentioned can take care of the issue without disturbing the deeper sand bed.
I wouldn't do a lighted refugium, macroalga and corals are competing with each other and macros can dump stuff into the water that can affect corals negatively in several ways. A cryptic refugium with just rubble and cryptic sponges can be very beenficial as cryptic sponges can remove stuff from the water much faster than bacterioplankton and convert some of it into stuff corals can use.
Here's some links you might find interesting:
"Coral Reefs in the Microbial Seas" This video compliments Rohwer's book of the same title (Paper back is ~$20, Kindle is ~$10), both deal with the conflicting roles of the different types of DOC in reef ecosystems. While there is overlap bewteen his book and the video both have information not covered by the other and together give a broader view of the complex relationships found in reef ecosystems
Changing Seas - Mysterious Microbes
Microbial view of Coral Decline
Nitrogen cycling in hte coral holobiont
BActeria and Sponges
Maintenance of Coral Reef Health (refferences at the end)
Maintenance of Coral Reef Health
Optical Feedback Loop in Colorful Coral Bleaching
Optical Feedback Loop in Colorful Coral Bleaching / Curr. Biol., May 21, 2020 (Vol. 30, Issue 13)
DNA Sequencing and the Reef Tank Microbiome
Aquabiomics: DNA Sequencing and the Reef Tank Microbiome
Richard Ross What's up with phosphate"
What's up with phosphate? by Richard Ross | MACNA 2014