If you have just bought your first coral frags, or you are about to start fragging, a rack is one of the first things worth sorting out. Here is what they are, the types you will meet and how to get one working.
What is a frag rack?
A frag rack is a small frame that holds coral frags in one place, so you can see them, feed them and move them without disturbing the rockwork. Most racks are made for frags fixed to plugs. Some sit in a display tank, others in a separate frag tank.
Reef keepers use them for new corals settling in, for frags growing on before they go on the reef, and for corals being grown to share or sell. A rack keeps each frag at a known spot, which makes it far easier to check on them one by one.
That is all a rack is: a holder. What changes between the types is how it is held in the tank, and that decides where it can go.
It also helps with the small jobs. When every frag has a fixed place, you can feed one coral directly, treat one coral, or take one out for a friend, without hunting through rock for the right plug.
The 3 types: magnetic, standing and egg crate
Our magnetic frag rack is mounted by magnet on the glass, so you can put it where you want and reposition it as corals grow. It comes in 3 sizes, Mini, Slim and Standard.
Our standing frag rack V2 is placed at the bottom of your aquarium to help new corals acclimate to their environment. It comes in 2 sizes, Mini and Standard, and it needs no glass or magnets. It suits corals that will spend their first days low in the tank.
Egg crate is a grid panel with square openings, usually cut to size and propped in the tank.
It is a familiar, simple way to hold frags. We do not sell it, so we only cover the basics here. Our guide to magnetic vs standing vs egg crate compares all 3 side by side.
The types are not rivals. Some reef keepers use more than 1, with a standing rack for new arrivals and a magnetic rack for frags that are ready to be seen at eye level.
How to use a frag rack, step by step
- Pick the type. A magnetic rack goes on the glass, a standing rack on the tank floor.
- For a magnetic rack, measure your glass and choose the magnet strength that matches. Our guide on which magnet strength suits your glass shows how.
- Fix each frag to a plug with glue or putty and let it set.
- Put the rack in position. For a magnetic rack, place it in the tank with the outer magnet on the dry side of the glass.
- Set the plugs on the rack with a little space round each frag.
- Check the rack again after a day, then keep an eye on how the corals settle. If a frag looks unhappy, move it rather than waiting.
Where you put the rack matters as much as which one you buy, and our guide on frag rack placement covers that, including how to match light and flow to the coral without chasing numbers. Often the fix is a small move, not a new rack.
Plugs and docks that go with a rack
Our black coral frag plugs come with a 25mm round top or a 27mm square top, and both are 20mm tall with the stem on. The top is textured with a central divot for glue or putty. The stem is detachable, the plugs sink, and they come in packs of 5, 10 or 20.
The FragDoc is a small dock, 18.5mm tall and 15.5mm across, that glues to your rockwork and holds a plug. You can lift, swap or rotate a coral whenever you like. Plugs are sold separately. It is aimed at fraggers who like to rearrange, as the plug lifts out of the dock without a fight.
How many plugs a rack holds depends on plug size and rack footprint, so check the dimensions below against the plug you plan to use. We do not publish plug counts. Both are in the frag plugs and docks collection.
Rack sizes from the live dimensions
| Rack | Length | Width | Height |
|---|---|---|---|
| Magnetic Mini | 103mm | 67.25mm | 38mm |
| Magnetic Slim | 151mm | 39.25mm | 38mm |
| Magnetic Standard | 175mm | 81.25mm | 38mm |
| Standing Mini | 103mm | 58mm | 51mm |
| Standing Standard | 175mm | 72mm | 51mm |
Frag rack sizes are easy to misjudge from a photo, so lay a tape measure along the glass or the tank floor before you order. Remember that a magnetic rack also needs clear glass on the outside for the outer magnet. Mini is the compact size, Slim is long and narrow and Standard is the largest.
All 3 magnetic racks stand 38mm high and both standing racks stand 51mm high, so the choice comes down to length, width and the space you can spare.
If none of these fits your tank, we also build custom racks to measurement, including a 3 tier hybrid design made for a small frag tank. See our custom 3D printing page.
Which type should you choose?
Match the rack to the glass and the space you have. 3 quick questions settle most cases.
- Want to move the rack as corals grow, and your glass is within the magnet rating? A magnetic rack suits you.
- Glass too thick for the magnets, or you would rather keep frags on the tank floor? A standing rack needs no glass.
- Want the simplest set up and happy to cut it to size yourself? Egg crate is a fair choice.
Whatever you choose, think about growth. A frag that fits today may outgrow its spot in a few weeks, so leave room to move things, and read our guide to where to put a frag rack before you commit to a position.
Browse the frag racks collection to see every size and colour. The racks come in 5 colours: Midnight Black, Scarlet Red, Aqua Green, Clown Orange and Regal Blue.
