Although they come in different configurations than conventional aquariums, plastic storage containers or prefabricated tanks are ideal for spawning marine aquarium fishes. They are made by many different manufacturers and are available at many supermarkets, hardware and department stores. They are usually wider, come in a variety of sizes and shapes and offer a larger surface-area-to-volume ratio. Plastic containers have many advantages for aquarists establishing a fish room on a central filtration system since they are easily drilled with a basic power tool and holesaw attachment. They are usually available in dark colors that make painting unnecessary, are stackable and easily transported, and are usually quite economical.
But there are drawbacks. Soft plastics will sometimes degrade and leak contaminants into the water. Although I have never had a problem with this, it is a fact to consider. The quality of plastic used to make the container will usually determine if it will be suitable to house fish.
To convert plastic storage containers into a viable habitat for both the aquarist and the fish, a viewing window must be installed. Acrylic, including the Plexiglas brand, is available from a variety of sources and different manufacturers. Local plastic specialty shops may have piles of scrap plastic, with the protective paper still intact, left over from other jobs and available at a fraction of the price. Generally, 1/4-inch works well for all applications. Acrylic, not glass, must be used for the viewing window. As the tank is filled with water, the sides will bow from the water pressure. If glass is used, the pressure of the flexing walls will definitely crack it or break the silicone seal. Acrylic is easily drunk and has a certain amount of flexibility.
The viewing window should have at least a one-inch frame on all sides. A small hole is drilled in the side of the container to accommodate the blade of a jigsaw which is then used to cut out the reminder of the window. The corners can either be rounded or square, although rounding them both easier and more aesthetically pleasing. A piece of clear acrylic sheet is cut to fit tightly inside the container, extending beyond the edge of the window opening by an inch or more. The acrylic is positioned and marked for the location of the bolt holes that will be drilled though the acrylic and into the container. If the container is smaller than 20 inches wide on a side, eight bolts will suffice, at each corner and midpoint. If the container is larger than this, bolts should be placed every three to five inches.
Stainless steel, aluminum, and plastics can be used for this application. Saltwater is very corrosive and most fasteners will eventually degrade. The bolts will be sheathed in silicone, making them waterproof and corrosion-proof.
After the holes are drilled, a bead of silicone is spread evenly over the inside of the frame of the hole cut in the container. The acrylic viewing window is then laid in place and the bolts fastened. Silicone is used to cover the bolts. Twenty-four hours later, this indestructible tank is ready to use.
Another very useful application of plastic tanks is in housing pelagic spawning species. Square or rectangular tanks are not suitable for these species, as the eggs must be collected soon after spawning. A circular flow of water created from a return pipe and a siphon box fitted to the tank create an ideal egg collector. Pelagic spawners often fail to reproduce in shallow tanks as they can not complete or initiate a spawning assent. Fifty-gallon plastic drums are commercially available from a number of sources. Fitted with acrylic windows and specialty plumbing, these tanks are suitable for angelfishes and basslets. The return line to the tank is placed on the bottom of the tank and water is allowed to rise to the bulkhead drain at the top in a circular and upward flow, bringing eggs to the collector.
Source by Barbara Stec