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Week 15. How To Make Saltwater

Making your own saltwater can be a bit confusing or intimidating at first, but it is a pretty simple process! You may have also heard that you can buy saltwater from a local fish store. That is true, but it is more expensive in the long term, and it gets worse with larger tanks. Considering most saltwater aquarists do water changes every week to every month, you may go through quite a few gallons of saltwater per year!

So how much would you save making your own? Well on 200 gallons of saltwater, you would save about $115! This may vary depending on your local store, but either way it will be cheaper to make your own in the long term. Watch the video below and read the rest to learn how to make saltwater! 

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Table of Contents

This Week's Video:

The Gear You Need To Make Saltwater

While making saltwater is pretty easy, you still need some gear to be able to make good saltwater, and make it as efficient as possible. 

  • Salt Mix- We have used many different types and brands of salt mix, ultimately they all work well. If you are unsure, just go with the Red Sea Salt-blue box.
  • Food Grade Bucket or Trash Can If you have a small aquarium (30g or less), the standard five gallon bucket with a lid works great. For larger setups, we recommend the 20 or 32 gallon food grade Brute trash can with wheels (dolly).
  • RO/DI Filter– Go with either the MD Kleanwater 4-stage advanced RODI system for $200, or if you can spend the money, the Aquamaxx Puratek Deluxe 4-stage. DO NOT USE TAP WATER! If you do not want to get an RODI, you can buy distilled water or RODI water from your LFS.
  • Powerhead- Newa mp 1200 or equally strong, just to help with proper mixing of the salt.
  • Heater- Any normal heater will work just fine.  MD sells Eheim Jager’s and ViaAqua and Hydor glass heaters, which aren’t expensive but get the job done. If you did not know, you need the RODI water to be closer to your aquarium water temperature, as it affects salinity! 
  • Refractometer- Used to actually measure salinity, and is basically the same across different brands.

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The Step-by-Step Instructions

  1. Make sure you have all the necessary gear, plus a few towels.
  2. Get enough RO/DI water- you can always buy pre-made RODI water from your LFS or distilled water from a grocery store.
  3. Fill your bucket/trash can with the freshwater, leaving a few inches from the top to allow for mixing in the salt.
  4. Place your powerhead and heater inside, and plug them in.  Set your heater to match the temperature of your aquarium, and get the temperature as close as you can!
  5. Follow the directions on the salt mix, estimate how much salt you will need. Using a measuring cup, slowly add the salt to the water. 
  6. Take your time adding the salt, as dumping in large amounts all at once can lead to precipitation, which can not only mess with the calcium & alkalinity levels of the mix, but can also coat your pump and heater.
  7. If you do not have a powerhead, be sure to constantly stir the water. 
  8. We recommend saying the number of the scoop out loud or otherwise tracking it, to help remember which scoop you are on, as it is surprisingly easy to forget! It is normal that the water will be a bit cloudy during this process.  
  9. After a few minutes, use a refractometer or a salinity probe to test the salinity of the water. If it’s too salty, add a bit more RO/DI water and if it is not salty enough, add more salt. Be sure to wait a few minutes after adding salt or water before testing again, as you need to allow the the salt to mix.
  10. It’s best to allow the new salt water to mix for several hours, even up to an entire day. I usually make a new batch of seawater immediately after a water change, so I’m ready for the next week.
  11. If you are going to use newly made salt water right away, be sure that the temperature closely matches that of your aquarium and that there are no clumps of unmixed salt at the bottom.
  12. Never add salt directly to an aquarium as it could damage or kill your livestock.
  13. You can store salt water indefinitely if you follow a few simple steps: Have an air tight lid on your container to avoid evaporation. Allow no light so no algae or anything grows. Store your water in a cool spot, and even consider leaving in the powerhead and heater so it stays properly mixed and fully ready to use in case of an emergency!

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