Acclimation Guide


Acclimation is the process of adjusting your livestock to the water chemistry of their new home.  It is an absolute necessity whether you purchase animals from your local fish store or have them delivered.  The basic parameters you are trying to match are temperature, salinity, and PH.  If you keep test strips on hand, it is a good idea to check both the shipping container water and the water in the aquarium before you start and again before you release.  The initial test will give you some idea of how slowly or quickly you will need to proceed.  As rules of thumb – the greater the differences in PH and salinity, the slower the water change, the poorer the quality of the containment water, the larger the volume of initial water exchange. The final testing will ensure that you have met your acclimation goal. Always acclimate fish and invertebrates separately because we use Copper and other medications (Nitrofuracin Green etc) which are harmful to invertebrates.  


Most aquarist will have the recommended list of items on hand as part of the routine maintenance for a saltwater tank.  Note that the bag should remain sealed until you are ready to begin the acclimation process to minimize the rapid decline of the shipping water quality from air exposure.

Test Strips or Reagents

The strips are quick, reliable and easy, but the reagent methods are also suitable.

Test for PH differences between the arrival water and the aquarium water.  The greater the difference in PH, the more time you should take to acclimate.  You can expect a low PH in the shipping container due to the increased CO2 levels and temperature changes.

Test for Ammonia and Nitrite.  A high concentration of ammonia and to a lesser extent, nitrite (created by waste during transport – often you will detect an odor from the bag as a clue to these potential problems) would suggest using larger quantities of water for the initial water exchanges to achieve a safer environment.


Check the difference between the shipping water and the aquarium water before you begin.  The greater the difference, the smaller the quantity of new water after the initial 50% addition.


The small digital type with a probe is the easiest to place and quickest to register temperatures but any thermometer will work.  First take the temperature of your target tank then leave the thermometer in the acclimation chamber as a monitoring device.  If the temperatures begin to diverge, while doing an out -of –tank acclimation, you may want to place the container in-tank for 20 minutes before releasing the newest addition.

Acclimation Container

Acclimating container should be sized to hold 5 times the amount of water in the shipping bag.

The actual process can take place in the shipping bag floated or attached to the inside of the tank (be sure to use only plastic clips if you choose to attach the bag), or in a small bucket or bowl next to the tank.  The larger acrylic hang-on boxes work well for in or out of tank acclimation, with or without the shipping bag (preference and space are most often the determining factor rather than any rule of thumb).  I prefer to use a small container that is outside the tank rather than floating the bag to avoid accidental sinking.  If you have several items and don’t have the right containers, you can also slit the top of the bag and prop it up in the shipping box along with the other items being acclimated.

Quarantine Tank

The quarantine tank should contain water from your main aquarium (water removed for normal water changes is ideal if the water is removed from the middle of the tank), can be bare bottomed and will need at least a seasoned sponge filter for aeration and circulation (a small hang on filter also works well but provides no biological filtration).  Using the minimum setup will require daily water changes (continuing to use your main tank water) and waste removal.  Using the main tank water (rather than “”clean”” saltwater), allows for just a simple temperature acclimation after the quarantine period.

Fish vs. Invertebrates


Most invertebrates should be released into the main tank after water chemistry match.  They typically carry few contagions and fair better if they are allowed to acclimate to their environment immediately.  They are generally more sensitive to PH and salinity changes than fish and do not generate as much waste during containment so their acclimation time can and should be slower.
Although sea stars are notoriously sensitive to PH and salinity changes, should never be exposed to air and often require a minimum of 4 hours to acclimate, the sea serpents and basket stars are the most hardy of the group and adjust well using normal acclimation procedures.


Fish are generally hardier than invertebrates but can develop contagious symptoms when traumatized.  All fish harbor some parasites and biological pathogens (as do all living things, including humans).  These are normally not a problem to the fish or tank mates once the fish over comes the shock of transport and adjusts to an aquarium environment.  Your fish will be in a sensitive state on arrival and should be first acclimated to a quarantine tank for a minimum of 1 week (many experts recommend 3 weeks, depending upon the contents of your main tank).


Getting Started

After testing your target tank for PH, salinity and temperature, and having all your containers in place – remember, the water quality will begin to deteriorate rapidly once the bag is opened – slit the bag and gently pour the water and livestock into the appropriately sized container.  Test the container water for PH, salinity, temperature, ammonia and nitrite.  If there is a considerable difference in PH or salinity between the container water and your tank, increase the time between additions of more water.  If there is detectable ammonia or high nitrites, decrease the time or  increase the amount of  new water to bring the toxic state under control.

Adjusting the Water

The next step is to slowly add tank water to your acclimation containers in a series of regulated additions.

  • The first addition should be approximately 25% of the volume already in the container.
  • Wait 15 minutes – 10 minutes if there is a dangerous amount of ammonia or nitrites in the container.
  • Repeat the 25% addition of tank water as described in the first step so that your new arrivals are in 50% shipping water and 50% tank water.  This will have brought the temperature, salinity, and Ph to half way between where it was and where it needs to go.  It will also have diluted any waste metabolites to 50% of what they were and should be bringing relief to any stressed critters.
  • Wait 15 minutes or 20 to 25 minutes if adjusting to extend the acclimation time.  If you noted a big difference in water chemistry or temperature, this would be a good time to slow the process down by decreasing the amount of water added or by increasing the wait time.  Do not exceed 1.5 hours for the full process.
  • Add more tank water at the same original 25% volume or half that amount if adjusting by volume.
  • Wait 15 minutes or 20-25 minutes if adjusting by time
  • Continue the process (one more time if 25% additions have been maintained) so that at the end of about an hour you have one part our water and four parts your water.

Releasing the Livestock

At this point it is safe to introduce your livestock into its new home.

  • Place the container near or in the aquarium but do not submerge the container.
  • Gently remove the livestock from the bag or container with your hand and place it into the aquarium.
  • When placing livestock in with other inhabitants, observe your new addition for at least 20 minutes.  This is a precarious time for the new additions.  They have no established territory of their own and existing tank inhabitants may not immediately accept encroachment.  More aggressive feeders may mistakenly think anything being put into the tank means it is feeding time and attempt to consume a new crab or shrimp.  Be prepared to run interference for the first few minutes.
  • Discard the acclimation water.  Our fish will be packed in “green” water to help ensure their healthy arrival.  The water is supplemented with nitro-furazone, a nontoxic, broad-spectrum antibiotic that is fish safe but could negatively affect your bio-filtration and some sensitive invertebrates.

That’s it! Enjoy your newest additions to your fish tank! We are glad we could supply them for you.