SA-Aquarium
(Acetic Cure, Silicone Adhesive / Sealant)
APPLICATION & USAGE GUIDE
1. General information
Building an aquarium starts with using non-toxic materials. Normally a silicone based adhesive is used for bonding the parts together and for that it is important to use one without toxic ingredients like for example fungicide, as even the smallest dose can eventually harm or kill the fish. Most silicone based sealants and adhesives contain fungicide because this prevents fungal growth and therefore discoloration and deterioration of the material. Many silicones are too elastic and therefore too weak to be used as a strong construction adhesive.
With those basic requirements in mind, Sealants Australasia has developed SA-Aquarium. A strong and safe one-component adhesive designed for the construction of glass constructions like fresh water aquariums, sea water aquariums and terrariums, free of toxic ingredients. After application the silicone reacts and cures with atmospheric moisture to form a durable rubber seal.
2. Calculation of suitability
In general we do not recommended SA-Aquarium Silicone to be used for aquariums containing more than 1000 litres of water and / or higher than 60 cm. However, the content of the aquarium is not really the main criterion and serves more as a guideline. The main focus must be to prevent too much pressure on the adhesive. We consider 1 kg/cm² (which is 0,2 Mpa or N/mm2) as maximum for this. When the water pressure is known, as well as the total surface of the bonding substrate, based on this standard we can determine if the SA-Aquarium Silicone is suitable for a certain construction.
For example, consider an aquarium to be 200 x 50 x 60 cm (length x height x depth) with a glass thickness of 1.2cm.
First of all, laws of nature prescribe that the pressure on the sides of the aquarium is determined by the height of the water, not by the amount of litres inside the aquarium. Even if there would be 1000000 litres of water in a much bigger aquarium with the same water height of 50 cm, the pressure on the sides will still remain the same. Since the aquarium in our example is 50 cm high, the water depth varies from 0 cm on top to 50 cm at the bottom, making an average of 25 cm. Every 10 meters of water depth gives a pressure of +1 kg/cm² (starting from zero at water surface), so an average of 25 cm of water will result in 0,025 kg/cm². The largest side glass panel is 200 x 50 cm² = 10.000 cm². The total force on this panel will be 10.000 x 0,025 = 250 kilo. This force has to be carried by the sealant. The total length of the adhesive stroke, needed to bond the largest glass panel against two side panels, is 50 + 50 + 200 = 300 cm. The thickness of the glass is 1,2 cm and therefore the total surface of applied adhesive on this joint will be 300 x 1,2 = 360 cm². To prevent the large glass panel to be torn off from the side panels due to the water pressure, this 360 cm² of adhesive has to hold at least the weight of 250 kilos, which comes down to 0,69 kg/cm² . This is below the limit of 1 kg/cm² so SA-Aquarium silicone can be used.
3. Special remarks
We have experienced that in relatively large (high) aquariums, most often laminated glass is used, Acetoxy based products like SA-Aquarium Silicone cannot be used in combination with this type of glass as it might cause delamination. However in those kinds of larger constructions, the glass should also be placed in a metal frame, because no silicone will be able to withstand very high water pressure. Between the glass and the metal frame, rubber blocks with a Shore-A hardness of at least 70 should be used. This as the blocks and sealant will together hold the pressure of the water. In this case the main function of the sealant is to make the construction water tight. A 100% undiluted, oxime based silicone (Such as SA Silicone N-10), without fungicide, can be used for doing so.
4. Glass and joint dimensions
For selecting the glass-thickness of the sides and the bottom of the aquarium we advise to follow the DIN 32622 norm. As a joint thickness between the sides and between the sides and the bottom, we recommend 1 to 2 mm.
5. Surface preparation and finishing
To ensure a good adhesion, the glass has to be completely clean, dry and free of all dust and oils. For cleaning we recommend a clean rag, and a white spirits wipe. Finish internal angles as a triangular joint of 3 to 5 mm wide, depending on the water level. The adhesive must be fully cured (average curing speed 2 mm per 24 hours), before the construction can be transported or filled with water. After the adhesive is cured, rinse the construction several times with water before taking in use.
6. Limitations
SA-Aquarium Silicone is not paintable. Applied adhesive between glass to glass might contain small air bubbles that stay visible after curing.