Just Like Diapers, This Needs To Be Changed

Even a seemingly simple task like changing your tank’s water is crucial to the long term success of your saltwater aquarium. And there are several key steps that cannot be missed if you want your tank to look great.

In this episode of Mr. Saltwater Tank TV, I’ll take you through how to a water change step by step including showing you how I do water changes in under 10 minutes.

Links in this video: www.mrsaltwatertank.com/refractometer

Browse the Store! Questions?

Comments for this article (46)

  • daragh jones says:

    Hi Mark

    i have a 400 ltr tank and do weekly changes of 60 ltrs

    do you think this is enough to maintain my tanks params



  • daragh…from a straight percentage stand point yes (you could actually do weekly changes of 20L and be fine).

    However, you still need to test your parameters to see how much Ca/Mg/Alk, etc is being consumed by the animals in your tank. Only by testing parameters will you know if your water changes are enough to meet your tank’s needs

  • Mike says:

    Alright, I believe you that it was under 10 mins, but you neglected to: change your filter sock, empty and rinse your skimmer cup, and top off your R/O. All good ideas to do whenever you do a water change, right?

    And we both agree that preparing and testing the water took some time as well, though those Hanna checkers are AWESOME! 🙂

  • Byron says:

    Great idea to shake the bucket! Proactive/reactive. Thanks Mark!

  • aron lockhart says:

    Hey Mark,
    If I have a 45gal tank how much water do I change a week? and I want to get coral reef for the first time. So should I change the sand and what type of filter should I have? I’m asking you b/c I just don’t know if my saltwater store is trying to get more money. Also I don’t mix my saltwater it comes pre mixed.

  • Steve says:

    I have a 180 gallon rock / fish tank and am just getting started in my new passion. What size of water changes should I be doing on a weekly schedule? Thanks Red

  • http://www.youtube.com/watch?v=AVVXg6DbwQc hey Mark I asked a question earlier and thought you should watch this

  • Mike…I usually do all those things during the course of the week. Sometimes I have to do that stuff on water change days and yes, when I do, it takes longer than 10 mins.

    And, when I’m in a time crunch, I do the “quickie” water change like you saw above. Therefore I can’t use “I don’t have time” as an excuse!

  • Ayme says:

    Hello Mark,
    I love your stand, where did you buy it?
    Did you build it?
    I would like to have one of those.

  • Hey Mark,

    If I have a 45gal tank how much water do I change a week? and I want to get coral reef for the first time. So should I change the sand and what type of filter should I have? I’m asking you b/c I just don’t know if my saltwater store is trying to get more money. Also I don’t mix my saltwater it comes pre mixed. This tank is 5-6 yrs old I’ve had it for 5months

  • Debbie says:

    Hi Mark –

    Can you tell me where you get those white water jugs you have? They look so much easier than what I have and I think you said they are 5 gal jugs, right?


  • All of the local fish stores carry them. Try there first.

    You can always use a brand new gas can. Not as easy to get salt down the neck, but any hardware store will have them.

  • zac (zacguitarshreder12) says:

    yay you made the water change video like a sugested a few months ago

  • Ayme says:

    thanks for answering the Q. about the stand.
    never got it.

  • Ayme..the stand was custom built and I’m waiting an ok from a carpenter to put you in touch with him so you can get one for yourself. I need his ok to share his information first.

  • thanks for the suggestion Zac!

  • ayme says:

    Thank you very much for the info.
    yes I would be interested in order one.

  • ayme…something is up with your email addy as I tried to contact you to give you the carpenter’s name. Can you contact me via the form on my site: http://www.MrSaltWaterTank.com/contact/

  • Ayme says:

    Hi Mark,
    I have rewrite my e-mail.
    let’s try again,.
    Thanks a million.

  • Kyle says:

    This sounds funny but I always do a taste test to make sure its saltwater and not fresh lol

  • Dan says:

    Hey Mark,

    When you do a water change, do you shut down your return pump? The water level in the last chamber in my sump gets too low in order for me to pull a full 5 gallons out with the pump running.


  • Meek says:

    Good info for those just getting started. You’re getting them started right. Keep’em coming!


  • Dan..yes, I shut down all my pump except for 1 of my vortecs

  • Arnel Cruz says:

    Hi Mark,

    I currently do a 2 pail change every once a week.
    Do you think this is adequate for my closed system?

    I have the 83 gallon with a 30 gallon sump,so total volume of water you stated to me was 75,due to my LR in the DT…

    I do the 24 hour pre mix method and do a straight pull 2 bucket and relenish with the new mixed salt water…
    Do you think I should change anything up…

  • Sounds good to me. Of course watch your tank and see how everything responds. If stuff freaks out, back off.

  • Hey Mark,your videos are great! it gave me a good insight on what i should and should not do with my tank.thanks for that constant reminder’know your tank’s personality’.cheers!

  • Eric says:

    Hey mark, thanks for all the good videos. Im about to set up my first saltwater aquarium and its going to be a 29 gallon… Im learning alot from you. In one of ur videos you said your first tank was a 29 gallon and you made lots of rookie mistakes. Could you maybe email me and list somethings i should or shouldnt do? Thanks again and GORGEOUS TANK!

  • Robert says:

    Nice video and good solid tips as always. However, where is the link or name to the recommended refractometer? And yes, the actual switch out was done within ten mins, but you neglected the mention of the one hour prep time. Also, a good tip is to get the wife and kids to help carry jugs of water and make it a wonderful family weekend project.

  • Robert…

    refractometer: http://www.mrsaltwatertank.com/refractometer

    It takes me about 5 minutes to mix up my salt. Perhaps it is time for another video.

    Great idea about getting the kiddo to earn his keep! Right now he just lights to chew on the screw top lid for my 5 gallon jugs.

  • Rick says:

    I’d suggest putting the “new” water into the display and NOT the sump … and keep it a degree or so cooler than the display water so the “warmer/older” water overflows to the sump.

  • Dusty says:

    What brand and size of powerhead do you use that fits inside the 5 gal container?


  • Dusty…I actually robbed it from an old media reactor. i have found that a Koralia nano fits down the neck of the jug.

  • Ray says:

    the link to the recommended refractometer is not working and I really like to get one becasue the swing arm one that I have is a joke, so I would like to know the one you recommended.


  • Ray…here is the corrected link: http://www.mrSaltWaterTank.com/site/refractometer. Thanks for the heads up

  • Chris P says:

    Just ordered my Buckeye Field Supply RODI unit. Can’t wait.

  • Peter says:

    Hi Mark,

    I’m seriously thinking of getting the Genesis RENEW auto water change system. Have you heard any reviews on the system?

    You can set it up to change a certain amount of water over a given period, and it changes a gallon at a time. Would a system like this be beneficial, not just for ease of changing water, but by adding the water at smaller intervals.

  • Jeanette says:

    Since I have cats, I’ve found the plastic cat litter jugs work great for tank water. Just rinse them out well before using them. 🙂

  • chris says:

    What brand refractometer is that?

  • John Fusco says:

    Hi mark what is a good salinity level for my live rock fish only?? Thanks

  • John…even for a FOWLR tank, I prefer 1.024-1.025

  • Karen Crotty says:

    Mark, just a quick question. How large of a water change would you recommend for a 75 gallon tank if I change to weekly instead of monthly like I have been doing (which admittedly is a pain in my rear)? Would 5 gallons be enough, or should I do 10? I am currently fighting an algae issue, so does this affect the size water changes until it clears up? Thanks for the advice!

  • Karen…a 5% weekly water change is what I recommend. Doing large water changes won’t do much for your algae issue as you need to do LARGE >50% water changes to bring nutrient levels down.

  • Terrie Bissonnette says:

    I have searched your site and cannot find where you mention what brand of refractometer you are using. Can you email me the brand you use? I am considering the Marine Depot one, but bulk reef supply has one but it has to use seperate calibration fluid which I’m not fond of. Do you have experience with the Marine Depot one? thanks for your reply.

  • Terrie…I recommend calibrating your refractometer every month so I wouldn’t worry about one brand requiring calibration fluid.

  • SantaMonica says:

    Really good point about shaking the salt before mixing it. Never thought about that before.

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