Will PVC Glue Hurt Saltwater Fish?

PVC pipes are the type of fixtures that you might not think of as aquarium equipment, but they're indispensable. In the saltwater aquarium, you can use PVC pipe to create simple caves for shy fish or use it as a frame to keep rockwork stable. Additionally, PVC serves to plumb sumps back to the main aquarium. If you need to glue PVC pipes together, take the right precautions.

  1. PVC Glue

    • Most PVC pipes are designed for use with human water supplies. This means they are rated to be chemically inert and safe for drinking water. When selecting a glue, make sure the label indicates it is "food safe" or "intended for potable water" or anything to that effect. Again, most PVC adhesives are designed to be safe for human drinking water, so you shouldn't have trouble finding one with this labeling. Most PVC adhesives need a primer. Check for the same "food safe" labeling on your primer.

    Cautions on PVC Glue

    • Always read the manufacturer's instructions carefully when using PVC glues. Some PVC glue is food-safe when it dries but may release dangerous chemicals when curing. If PVC glue takes a while to cure safely, avoid using it for applications like building live rock framework, since such applications require you to work quickly.

    Super Glue

    • Super glue or cyanoacrylate can be a useful alternative to PVC glue. When used with an accelerator, you can get super glue to quickly dry. Once dry, this glue does not leach chemicals into saltwater. The rapid set time provided by a super glue accelerator means it dries almost instantly, so it's ideal for applications like attaching live rock to framework and attaching corals to surfaces. Super glue can work better than regular PVC glue in situations with a time factor. For example, high-quality live rock may need to be secured to PVC fittings or pipes but cannot be out of the water for more than a second or two. Instead of a primer, roughen surfaces with sandpaper before using super glue on acrylic.

    Alternatives

    • Options to PVC glue and super glue exist. Pet shops sell "aquarium glue," food-safe marine silicon glue. Make sure you give aquarium glue 24 to 48 hours to cure before adding glued items to the aquarium, since it releases acetic acid when curing, potentially harming your water chemistry. Additionally, high-end fish stores that sell reef aquarium equipment often have products like reef glue and coral putty. These products are designed to cure quickly and safely in saltwater. Make sure any adhesive you use is either designed for aquarium use or labeled "food safe."