CORRECT AQUARIUM SILICONE APPLICATIONS; What Silicone to use and what not to use, Aquarium Repair, Aquarium construction.

*Also how to use silicone to repair an aquarium (three different applications)-
*DIY Aquarium Glass Thickness recommendations.


SILCONE BASICS:

Silicone rubber is a unique synthetic elastomer made from a cross-linked polymer which is reinforced with silica. Its characteristics are such that it provides a balance of mechanical and chemical properties useful for bonding glass aquariums (not acrylic).
The basic formula is: Me3SiO(SiMe2O)nSiMe3

RTV Silicones are the silicones commonly used for glass construction and is often sold in Home Improvement and Pet Stores (or online)
RTV Silicones consist of polydialkylsiloxane with terminal hydroxyl groups (groups made up of an oxygen atom and a hydrogen atom connected by a covalent bond), which are reacted with organosilicon (chemical compounds containing carbon silicon bonds) cross-linking agents. This operation is carried out in a moisture-free environment and results in the formation of a tetrafunctional structure (A chemical structure that possesses four highly reactive sites). Curing takes place when materials are exposed to moisture. Atmospheric moisture is sufficient to trigger the reaction, and thickness should be limited if only one side is exposed to the moisture source. Curing is also relatively slow, reliant on moisture ingress into the polymer which produces Acetic Acid vapors.

Different formulas and (combined with temperature and outside humidity) will affect cure time. Dow Corning and GE have proprietary formulas that cure at an even slow rate as compared to some cheaper formulas, especially used in construction where this is not an important factor.

100% RTV Silicone Rubber Sealant produces a flexible, durable weather resistant seal between similar and dissimilar materials; RTV Silicone provides excellent adhesion to tile, glass, porcelain, ceramic, fiberglass, non-oily woods, plaster, painted surfaces, metal, many plastics, and rubber. It will withstand temperature extremes from -60°F. to +450°F. and is waterproof for freshwater or saltwater use.
You will note that plastic (which is made from oil) is not mentioned. RTV silicone is not useful for bonding acrylic aquariums and the oils within acrylic will eventually cause peeling away (lack of adhesion).

AQUARIUM APPLICATIONS:

RTV Silicones are useful in the construction of glass aquariums and sealing the joints in DIY wooden aquariums. Silicone is NOT useful for acrylic aquariums as it will peel away over time due to the inherent oils in plastics.
Not all silicone formulas are the same, as stated earlier, Dow Corning and GE produce a RTV silicone that cures at an even and slow rate necessary for aquariums. Why is this important? Too fast a cure will not allow proper surface adhesion especially in important seams. It is also hard to work with in building aquariums and the person needs to work very quickly (usually too quickly) for proper aquarium construction.

Also you want to purchase pure 100% RTV Silicone as many (including ones produced by Dow Corning) have other ingredients for different applications such as fiberglass.

A good example of a silicone you do NOT want to purchase is Dow Corning Marine Sealant which I have actually seen recommended for aquariums! This product is great for fiberglass hulls of boats however it lacks the proper strength for aquariums due to added ingredients that allow for adhesion to plastic.





AQUARIUM REPAIR;

With a good silicone, you can perform a few repairs yourself.

For an older tank that is starting to leak (no broken glass), this can be repaired following these basic steps:
[1] Empty aquarium
[2] Remove ALL old silicone with a razor blade
[3] Clean and prepare surface with fine sandpaper.
[4] Make sure all surfaces are dry.
[5] Apply silicone (a caulking gun works best), making .5 (or smaller) cm. bead in the inside edges.
[6] Tighten all outside corners with strong reinforced dust tape. For tanks over 75 gallons I recommend wooden clamps.
[7] Immediately uses your index finger to smooth ALL inside edge beads into a smooth surface, quickly wiping away excess silicone.
[8] Your repair is complete in 48 hours.

For non structural corner chips:
[1] Drain aquarium down to the area of the chip.
[2] Inspect/ clean/ repair the inside area in needed.
[3] Clean out broken glass on the outside chip area
[4] Carefully clean out broken glass (gloves are recommended), a razor blade followed by fine sand paper works best.
[5] Inject new silicone followed immediately by a piece of glass that fits reasonably well into this chip.
[6] Add more silicone if necessary.
[7] Smooth repair and add a piece of wax paper (or similar waxy or mildly oily band aid), followed immediately by strong reinforced duct tape to hold this repair in place.
[8] This “band aid” can be removed in 24 to 48 hours and the aquarium re filled.

For broken plastic hinges:
[1] Remove old hinge
[2] Place both pieces of glass on a firm level surface
[3] Run a .5 cm bead of silicone carefully down the area where both pieces of glass come together.
[4] Immediately, using your index and middle finger, run these fingers over the top of this silicone bead forming sharp peak of silicone between both pieces of glass. Remove excess. Bare hands (fingers) work best as the oils present repel the silicone from adhering too much to your fingers. The silicone should look sort of like this after finished: /\
[5] After 24 to 48 hours your new and more durable hinge is ready.

FOR DIY AQUARIUMS:

Recommended Glass thicknesses:
(Length x Height x Width)

2 x 1 x 1 = 5mm glass
2 x 1 x 1.5 = 6 mm glass
2 x 1.5 x 1.5 = 8 mm glass
2.5 x 2 x 2 = 10 mm glass
3 x1 x 1 = 6 mm glass
3 x 1.5 x 1.5 = 8mm glass
3 x 2 x 2 = 12 mm glass
4 x 1.5 x 1.5 = 10mm glass
4 x 2 x 2 = 12 mm glass
6 x any size x 2 feet max. = 12 mm glass

Please note that the formula for gallon calculations is L x H x W divided by 231 = Gallons. Multiply this by 3.785 for liters.
I do NOT recommend a glass aquarium over 250 -300 gallons!



SUMMARY:


Can you easily purchase the proper silicone at a Home Improvement Store? The answer is yes, just do not purchase anything other than 100% Pure Silicone (color does not matter) and I strongly recommend brand loyalty as there are good reasons behind GE and Dow Corning patents. To be safe, if you are unsure of the silicone you are buying, do not try and save a few bucks at the local hardware store when your local Pet Store or Aquarium Store have the correct product for maybe a few dollars more (unless an exploding aquarium in the middle of the night is your idea of excitement).
If you can not find quality Aquarium Sealant (either Dow Corning or GE, which hold patents for a good reason), please click on the picture to the left for an online source.