How To Set Up A Frag Tank – Ultimate Guide

Setting up a frag tank can provide us with a couple of benefits.

This guide (updated for 2019) will show you the process and solutions on how to go about doing it.

Here are the basics of how to set up a frag tank:

  1. Purchase or reuse a suitable fish tank
  2. Decide on how the tank should be set up
  3. Prepare a list of accessories
  4. Set up and cycle the tan
  5. Frag the corals
  6. Introduce corals and other aquatic animals and plants
  7. Monitor and take corrective actions if needed


What is the purpose of a frag tank

There are a couple of reasons why anyone will want to start a frag tank:

  • Avoid clutter in main tank: Once you have grown coral to the point where your tank may become a bit cluttered, you’re probably wanting to start a frag tank.
  • Selling: One can also use a frag tank to sell corals for money without disturbing your main tank’s water environment.


Selecting a fish tank – How deep should a frag tank be

Selecting up a frag tank isn’t too difficult and you don’t need to go big. Below are the dimensions you can consider:

  • A 20 gallon tank is more than enough for a frag tank.
  • A shallow tank is best. They are easier to clean, and will have much better light penetration for growing coral. It is also easier for you to add or remove frags when they grow.
  • Recommended height is between 10 to 14mm. You are usually going to loss 1mm at the top and another 2mm from the rack. That leaves you with about 7 to 11mm of height space to work with. Any shorter and you might be limited to growing very small corals


Frag Tank Set Up Considerations

There are a few additional things to take into consideration before doing the actual tank set up.

  • Connected to main tank?: Decide in advance if you are going to keep your system separate from your main setup, or are you going to be combining them side by side? By keeping them connected, you will save cost esp on the accessories. For example, your main and frag tank can share the same lighting or the same plumping. However, I usually advise folks to keep it separate. This makes it easier when you need to treat the coral, or add in new coral to the tank itself. Also, if the main tank fails, it wouldn’t affect your frag tank.
  • Number of frag tanks: For those who are setting up frag tanks to sell their frag off, it makes it easier if you keep separate tanks with their own own plumping lines. You can easily disconnected and sell it off without affecting the other corals. The con here is that it will cost a bit more in equipment costs to set up, and operate two separate frag tanks.
  • Any fishes?: A big consideration is whether fishes will be in the frag tank. If it is your first time, I suggest having no fishes. Having them adds quite a bit of complication, especially on the treatment of water perimeters.
  • Separate slump?:  You might want to consider having a separate sump from the frag tank, which could help with the overall water stability. It also help to increase the volume of water in the tank since all the stuff such as live rocks, heater are placed in the slump.

(Editor’s note: The use of a slump is to collect unwanted water or waste from the tank. It is also used to store all the accessories to make the tank looks less crowded and unsightly)


What do you need for a frag tank

As with any nano reef aquarium, you need a list of accessories to ensure a healthy frag tank.

Must haves

  • Filtration: Corals are living things so they still produce waste. A filtration system is needed to clear the water up, although it can be a simple one.
  • Heater: Heating your frag tank is basically the same as the general rule for heating your aquarium, typically 3 to 5 watts of power for every gallon of water. A good heater for a frag tank is the Cobalt Neo-Therm due to its slim design that can fit into tight spaces.
  • Coral cutting tools: You will need tools to cut the corals. This includes coral cutting shears or saw, scalpel and gloves
  • Circulation Pump: Proper water flow is essential in a frag tank. You can use any regular power head like the Hydor Koralia. For a 20 gallon tank, one powerhead is more than sufficient. However, if you decide to go for 40 gallon and above, you will need 2 to get the bottom flowing as well.
  • Lighting: If you heed my advice on getting a shallow tank, then you don’t’ need a powerful lighting system here. Something like the AquaticLife Marquis, or the Kessil A360 can do the job. They are compact in design and can be chained together if needed. If your frag tank is deep, then you need led lighting for the corals to receive the necessary light for them to grow. For recommendations, check our article om the best light bulbs for frag tank.
  • Live rock: Help to stabilize the water perimeter organically such as providing filtration. It also provide a medium for bacteria, which is needed in the water. If you need recommendations, check out our guide on the best live rock for tanks. You can do away with live rock but you need to clean the water very frequently.


Optional accessories

  • Protein Skimmer: This is not needed if you don’t intend to keep any fishes. I advice first time frag tank owners to do without fishes in their first try
  • Frag Racks: This can be anything that can hold up the tank. Might not be a rack that is specifically built for frag


Setting up the tank – How to cycle a coral frag tank

After selecting the tank, deciding on the set up and getting all the necessary accessories, it is time to do the set up itself.

  • Prepare salt water
  • Place the live rock and filtration in the tank.  You can add the heater and lighting now or later.
  • Fill the tank with water and let it sit for a couple of days
  • Once the water is cycled, place the frags in (You can learn how to frag corals in the next section). You need to be creative here. One way is to stick the frags to the live rocks using stuff like rubber bands or toothpicks. Play around with it to see what works for you.
  • Feed amino acids to the corals to help them recover
  • Check the water daily in the first two weeks to make sure the perimeters are stable.
  • Change water weekly. The recommended percentage is around 20%.


How to frag corals

There are generally 2 types of corals: hard and soft.

For cutting hard corals, it is pretty straight forward. You can use a shredder or saw to cut off the part that will go into the frag tank.  I recommend cutting at the end of Y shape for a cleaner cut.

For soft corals, you will need more finesse as they are soft.  Usually, scissors will work best.  The tricky part is knowing where to cut as the correct spot differs greatly between species. I recommend you check out the details of the specific breed of coral online before doing the cutting.


Advantages Of A Frag Tank

However, on the positive side, if you were to set up two separate systems, and say one of them crashes on you, then at least you would not have lost everything. That said, this is extremely important to those who deal in high end corals. Another positive side to setting up two different coral frag tanks, is that it will help when it comes to testing out corals in different high lighting, and lower lighting to see which way the coral would benefit from better.



When it comes to setting up a frag tank, the many different choices out there to select from can easily be confusing to decide upon. However, we hope that some of our tips, and suggestions within this article here today can better help the consumer to now make a better purchasing informed decision for their own requirements. Finally, while these tips can help, we further suggest that the consumer spend a moment talking to professionals, who can further provide them with certain additional equipment they might need for their own set up to be completed properly for them with ease.

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