100% silicone is perfectly safe for aquariums as long as there are no sneaky additives; If it’s labeled as pure silicone, it’s safe. Some silicones even go so far as to say “aquarium safe” on their packaging, but this can often be reflected in the price.
Silicone Aquarium Sealant is ideal for building or repairing small aquariums. 100% silicone rubber formulation provides a waterproof seal that won’t crack or shrink. It is non-toxic once cured.
Regular silicone is often adulterated with anti-mold agents, which are ideal for a household project – but toxic to fish and plants. These chemicals will get into the water over time and potentially cause problems.
GE Type One Silicone is exactly what you are looking for. Type 2 contains a product called Bioseal to inhibit the growth of mold and mildew. All Glass aquarium silicone is the same as GE Type 1, only packaged for the aquarium trade and is therefore much more expensive. You want GE Silicone 1 door and window version.
What is the difference between GE Silicone 1 Sealant and GE Silicone 2® Sealant? GE Silicone 2® Sealant is a so-called “neutral curing” silicone, which means that no acids are released during the curing process (in contrast to GE Silicone 1 Sealant).
The high-strength silicone creates a permanent seal that will not crack or shrink and is non-toxic, making it perfect for all aquariums. For standard aquarium use clear and Black Seal aquarium use Black Sealant.
DAP 100% silicone is aquarium safe. I’ve used it many times in sump and overflow applications.
This high modulus RTV silicone sealant forms strong cohesive bonds to glass without the need for primers. The bindings are unaffected by constant water immersion and are non-toxic to fish.
when fully cured
It’s safe for incidental food contact and is dishwasher and microwave safe. It is also ideal for building or repairing small aquariums and, when hardened, is harmless to freshwater and saltwater fish.
Yes, Silicone I is reef safe.
It’s Red Devil 100% Architectural Grade Silicone. It should be fine as long as it doesn’t contain any additives to kill mold. If you use it, just make sure you let it harden for about 24 hours before putting it in the aquarium.