I am using GE Silicon II for glass and window (black and grey 30 min setting time) in my 90 gallon aquarium as sealant for over a year without any issue. My fishes are doing very good. There are a lot many parameters of maintaining a healthy aquarium. Many newbies don't know that and blame the silicon they used. I'll put a link to my aquarium video which was sealed with GE Silicon II at the end of this post. The few other points to consider before blaming GE II silicon are as follows:
1. The new tank has to be cured for at least a week or two to let adequate time to settle the silicon down
2. The new tank should be properly cycled for a month before dropping new fish
3. Some 3D background made of portland cement make the water very acidic. they should be cured for at least two weeks with frequent water changes and measuring water pH frequently before dropping any fish in them
4. After a through research, I found, GE Silicon II for kitchen and sink (red) contains anti mildew chemical added to make them for more mildew resistant but the GE Silicon II for Window and glass does not actively contain any added anti mildew chemical although the label anti mildew. They actually by formulation more mildew resistant than Silicon I but no 'extra' anti mildew chemical added. This is just to keep up with the 'anti mildew' slogan to make keep the sale higher.
5. Before dropping your fish in the newly cured and new aquarium setup, check all the water parameters like pH, Ammonia, Nitrite, Nitrate, Kh etc. to be safe.
To me GE silicon II worked pretty well and not causing any problem. All the above negative comments are speculative and guess works and not from personal experience or from not considering the points I mentioned above. Here is my tank https://www_youtube_com/watch?v=eu7MFrhVFeM
Change the _ with dots to watch
1. The new tank has to be cured for at least a week or two to let adequate time to settle the silicon down
2. The new tank should be properly cycled for a month before dropping new fish
3. Some 3D background made of portland cement make the water very acidic. they should be cured for at least two weeks with frequent water changes and measuring water pH frequently before dropping any fish in them
4. After a through research, I found, GE Silicon II for kitchen and sink (red) contains anti mildew chemical added to make them for more mildew resistant but the GE Silicon II for Window and glass does not actively contain any added anti mildew chemical although the label anti mildew. They actually by formulation more mildew resistant than Silicon I but no 'extra' anti mildew chemical added. This is just to keep up with the 'anti mildew' slogan to make keep the sale higher.
5. Before dropping your fish in the newly cured and new aquarium setup, check all the water parameters like pH, Ammonia, Nitrite, Nitrate, Kh etc. to be safe.
To me GE silicon II worked pretty well and not causing any problem. All the above negative comments are speculative and guess works and not from personal experience or from not considering the points I mentioned above. Here is my tank https://www_youtube_com/watch?v=eu7MFrhVFeM
Change the _ with dots to watch