Set Up a Saltwater Aquarium

A Step-by-Step Guide to Mixing Saltwater

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  1. Avatar Marco says:

    Hello Mr. Kurtz,

    My name is Marco and I am a senior at Minnetonka High School. I am writing on behalf of myself and my research partner in hopes that you could provide us with some quick advice on some difficulties we have encountered. For our research, we hope to investigate the recovery of Aiptasia Pallida, a marine anemone, under different temperature conditions. However, in setting up our marine tanks(four ten gallon tanks), we made mistakes. In hindsight, our mistakes seem silly, but we would like your opinion on how to address them. Here are our main errors:
    When mixing in the salt mixture, we used conditioned tap water(but not DI water). We now have access to DI water.
    We mixed the water in our tanks instead of in a separate bucket. We now have good buckets available.
    The buckets we used to gather the water were not high grade plastic. Our new buckets are safe plastic.
    To mix the saltwater we did not use a pump, but instead vigorously mixed each batch until it appeared to dissolve. We do not have a pump but could get one, is it very necessary?
    With all of these errors, our first Aiptasia that we added to the tanks died overnight. Moving forward, we were planning on a large water change(50%) with saltwater mixed correctly. Do you think this would suffice, or should we drain all of the water and start again? Any advice is welcome.

    Best Regards,
    Marco Conati

  2. Avatar Kevin says:

    Hi I’m mixing up salt water, my tank is running at 26c and has a salinity of 1.025. Iv just mixed up a drum of 75litres and its salinity is 1.025 but temp is 11’c will this change much once I heat it up to 26’c

    1. Avatar Jeff Kurtz says:

      Hi Kevin! Specific gravity is temperature-dependent, so you’ll want to heat the water to the desired temperature and then adjust the SG from there. Thanks for your question!

  3. Avatar Jane says:

    I bought salt water a few weeks ago I put it in the shed in a container will I still be able to use it

    1. Avatar Jeff Kurtz says:

      Hi Jane! That shouldn’t be a problem. Just be sure to aerate the water for a day or so and heat it to the appropriate temperature before using it in your tank.

  4. Avatar Michael says:

    hey man your tips are really useful but i want to know if i have a 90 gallon tank how many days would it take for me to fill my tank up the first time since u said u need to wait for the water to sit overnight


    1. Avatar Jeff Kurtz says:

      Thanks Michael! I wouldn’t worry too much about aging the salt water for your initial tank fill (before any livestock is added). That’s more of a concern for performing routine water changes once the tank is up and running. I failed to make that clear in the post.

      1. Avatar Michael says:

        Hey man thanks for the answer so I want to know can I pour RODI water to fill the tank and than mix salt the first time

        1. Avatar Jeff Kurtz says:

          As long as you don’t have any live rock or live sand in there yet, you sure can!

  5. Avatar Kathy says:

    Hi Jeff,
    Thank you for the wealth of CURRENT information, it has been a lifesaver for me and my fish when I can’t figure out what to do.
    Re: mixing salt. Sometimes I mix the salt water but can’t get to my water changes for a day or two. Is anything “bad” happening to my water over this period. Are things starting to grow in the bucket? Sometimes I leave the power head in, sometimes not.

    1. Avatar Jeff Kurtz says:

      Hi Kathy! Thanks so much for your kind words! It’s no problem whatsoever to mix up a batch of salt water and then wait a few days to do the actual water change. In fact, I often wait several days to a week or more before actually using newly mixed salt water. Nothing bad is happening to it in the meantime. Just be sure to keep the water aerated and heated to the desired temperature.

      Also, it’s a good to keep the container covered to minimize evaporation, which will increase the specific gravity of the water. If some evaporation does occur, no worries though. Just remember to add fresh water to bring the SG back to the desired level (testing with your hydrometer, of course) before doing your water change.

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