Wanted to document some chronicles of this adventure over the past month. After determining it was not cyano I knew I needed to go a different route. First step I tried was to add my small 'mini' UV sterilizer ~3W which did not help whatsoever (probably due to small size).
I then rethought the issue. My first attempt to rid the invader at the beginning of April was by turkey basting the sand in sections over the span of a few days. Each section resulted in a large cloud that would consume the tank for hours. After the 3rd section on Day 4 I lost all of my acans and all corals were in bad shape. I immediately stopped this and the algae grew right back.
The next step in the journey as advised by
@brandon429 was to evaluate the cleanliness of the substrate. I never washed it prior to setup and I had cured my dry rock but it was by no means 'live'. Tank setup was about 8 months old and had a good battle with GHA/Bryopisis that I had beat so I was confident there was excess nutrients in the system in some shape.
We ran a few tests. For starters I started off by stopping all water movement and taking out the algae manually by removing around 3 cups of sand off the top layer of substrate. I rinsed in fresh TAP water, peroxide, and finished with an RO rinse and left overnight. The sand was no longer cloudy during the rinse. I promptly placed the sand back in the tank and enjoyed my sparking clean sand.....
After roughly 5 days the invader came right back.... strong as ever. This stuff never grew on the rock EVER. Out of curiosity we ran a few more tests. I set up a cup with saltwater from the tank and the algae and set on the ledge of the tank so it could get light. The algae slowly withered away. The last test we tried was to set up a cup with clean sand using water from the tank to see if we could get it to grow in the cup. No growth.
Next thing I tried was adding MB7 to try to encourage the bacteria growth to consume the excess nutrients. After 14 days with that.... No change...
Clearly the problem was in the sand bed.....
One last attempt, I lowered the lights significantly and removed almost all the white spectrum. No effect on the growth and 0 die back.
Given that fact that I would have to move the tank in a few months and it was a rainy holiday weekend (thanks Alberto). I decided to remove the ENTIRE sandbed and go bare bottom (this would make the impending move 10X easier anyways). Nothing crazy here, made 10 gallons of fresh saltwater, reused 10 from the tank, kept everyone in storage bins. Removed all equipment for cleaning (boy my refugium was dirty), removed sand, rinsed tank with a tap/peroxide blend and reassembled the tank.
The results......
WOW. I have literally never seen my tank water this clear . Not one coral loss, fish loss etc. I have saved some of the old water to perform an ATI ICP test here in the next week or so to see if there was something in the water from a nutrient perspective. I have seen coral start to grow again and corals opening completely.... After a week there has been 0 growth of the invader. Obviously way to early to declare victory but we are on our way. I also added 2 bowls of clean sand and placed the same frags that were on the sandbed before to see if anything would grow.... So far sparkling clean. I'm sure I missed some data points on this journey, and I will try to add more to this. Pics to follow......
