Crab's is about ready to throw in the towel.

[RedSea500MaxS]

Crabs! What the? You are our hero.

 

[DesertReefT4r]

Good to hear you are having success again. I too ended up removing all the sand, wish I would have painted the bottom black. Corals are surviving in my tank again and looking good. I can be hard at times.

 

[Fishinwall]

It wasnt bleaching at just the tips, it was everywhere. The base, the tips. The encrusting.

Mine is everywhere too..but it seemed to start at the tips after colors dimmed.

 

[clm65]

I'm not 100% but I believe nutrient spikes were to blame. The kessil H380 under the tank was reflecting light back up to the underside of the tank causing all sorts if nastiness growing under the sandbed. I had cyano (on the sand only, nothing on the rocks) and after doing water changes my nitrates would spike. So I took out the sand bed, painted the bottom of the tank to keep the fuge light contained in the sump and rebooted the whole thing. My acros and montis are showing great signs of recovery

I apologize if you already mentioned this, but how old was your sandbed?

 

[Crabs McJones]

I apologize if you already mentioned this, but how old was your sandbed?

We moved into the new house may of 2019, issues started around septemberish so 3 to 4 months old

 

[clm65]

We moved into the new house may of 2019, issues started around septemberish so 3 to 4 months old

Wow, I was expecting much longer!

 

[DesertReefT4r]

My sand was causing issues after just a year, amphidinium dinoflagellates. Removing all the sand fixed all issues I had at the time. Then ostreopsis dinoflagellates and GHA took over but corals are doing good so far. Still dealing with GHA mostly but my tank is slowly recovering and stabilizing again. Expect some issues shortly after doing something major like remove the sand. My sure you are aware of this though. My tank looked great for 2 weeks after removing the sand, then it looked like crap, now it's starting to look better again.