Sounds like a big ole tank crash to me. Way too many fish for that size tank and added too quickly. That grouper needs a 300gal tank. Most flounders need a 125gal or larger. It continually amazes me that people who have internet access don't do the research necessary to be successful in this...
You had all of those fish in a 40 gal? Are you sure it was the live rock that caused the problem? A panther grouper should be in a 200+ gallon tank. When you restock please be sure to research your fish before you buy.
This is what I found on another site.
Soft Corals and most Invertebrates should do fine with the Heniochus, but it may likely decimate Stony Corals, as they are a part of its natural diet.
I never said it doesn't happen. I suggested he check his seams and repair as needed. You must work for an aquarium supplier if you advocate replacing a tank because it's "old".
The old glass won't let go. A seam might but not the glass. A tube of silicone is a whole lot cheaper than a new tank. But if you inspect all the seams I'm sure they will all be fine. People worry about so many things in this hobby I sometimes wonder why it's still popular.
How can a canister filter leak because the power went out? I have the same filter. This is a sealed filter system. If it leaks when the power was out it would leak when the power was on.
The only way to know how good the Culligan water is to test it with a TDS meter. And remember you rarely get the rated GPD of any RO unit unless you have the correct water pressure and water temperature. How many stages is this Coralife unit?
I don't know this for sure but I would think a powerhead would not have much flow left with a 5 foot head. It might not even be able to produce any flow at 5 feet