Started the repair process. The complete self constructed reef with death reef were fixed with Quikrete hydraulic cement. Recommended in several forums. Result was the desaster shown in the Video. The cement gets like a liquid. Under sweet water it was a real good cement. Very strong. When stared to fill saltwater after 3 weeks it started to be a huge problem. So I needed to decide. All out water, corals and fishes.
I decided to repair in the running tank.
I ordered the Reef Bond in German. 2 KG. Result was very good. Easy to use, no fog of cement in the water and bonding strong and fast. Do not prepare too much while using. Binding very fast. Because I could only fix approx 15% of the reef I needed to reorder and decided to buy Stonefix from Aquaforest. Well compared to Reef Bond it is not this good and does not pay of buying lower price. While preparing the Stonefix I found out that you need approx 30% more because of extremly fast bonding and than the worse point you lose 50% under water. Does not mind how you prepare it, it gets lost in the water. A huge amount in the water and a bit at the reef. 6 KG and not even 20% fixed. Real bad.
Now I will try Nyos Reef Cement also to see which one is the best under Water.