Mr. Saltwater Tank

Terrible Advice Tuesdays (T.A.Tues): One Reason Why RODI Water Is No Good


Terrible Advice Tuesdays: RODI water won’t hold elements. Therefore, you need to use supplements to make your salt dissolve in RODI water.

The rest of the story: RODI water is “clean water” as most of the compounds and other junk in it have been removed. When you add an easily-dissolving solid (salt) to clean water, the dissolving party is ON!

Forget adding supplements to your RODI water to make your salt dissolve. Just add a powerhead to circulate the water and your salt will dissolve just fine.

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Comments for this article (26)

  • Matt says:

    I have no words for this one!

  • Mel says:

    It’s called tell people what they want to hear and sell that produce.

  • Mike says:

    Mel, maybe I should sell you a dictionary

  • JasonandSarah says:

    Mike, maybe I should sell you a personality?

  • Matt…no British saying comes to mind?

  • Alex says:

    Maybe Mark should sell us a new no nonsense guide to moving a saltwater tank 🙂 seriously Mark. I think that should be the next one. Keep up the good work bud.

  • George says:

    Additionally adding a heater with your power head helps. My RODI water is cold when I am done making up a batch I add the heater and powerhead 30 minutes before the salt to insure I get a fast clean dissolve.

  • Jeff from Milwaukee WI says:

    Mark,

    Is there any advantage of mixing salt with a heater and a powerhead for more than 24 hours?

    I currenty Mix my salt mix for 24-48 hours in 5 gallon buckets before adding the 5 gallons to the tank.

    Just wondering if I should turn the mixing and heating off after XX amount of time. Would rather not waste energy. Any Feedback?

  • Bob says:

    Percipitation is less likely if you mix the salt into the churning water when the water is cold. Just my .02

  • steve says:

    if the water isnt the correct temperature when you mix in the salt, the correct amount of salt will not dissolve. Warm water holds more salt than cold

  • Todd says:

    I only dissolve my salt for about 5 or 10 minutes. I stir it in until it’s all dissolved. Should I be allowing more time to dissolve my salt. I haven’t had any problems that I’ve noticed.
    Thanks

  • Jim says:

    I mix my salt following the manufacturers recommendation. My current salt brand says not to mix for more than 4hrs.

  • Bob says:

    The ph of your saltwater is very cqustic when first mixed, if you are doing 5 gallons on a large system it shouldn’t matter. If you are doing 5 gallons on a 40 gallon system, I would be concerned.

  • Bob says:

    *caustic.

  • Bob says:

    I might add, I never have leftover salt when mixing without a heater.

  • tony marshall says:

    Have used red sea coral pro for a few years I only noticed recently that you shouldnt mix itfor more than 4 hours and only heat when salt is fully dissolved,this is not the way ive been doing it for 25 years butit dosent seem to bother the inhabitants as long as I dont change too much at once

  • Ken says:

    I have never used RODI water in my 100 gal reef aquarium and it has been running for nearly a year with no loss of any fish or corals I just add declorinator to my water changes and mix my salt over night even my top off system uses tap water ( declorinated of course ) al of my mates do the same

  • bill says:

    i have a 500 plus gals. of saltwater flowing through out my house to 5 reef tanks . have been in hobby for over 20 plus yrs. when i do water changes on the tanks i add the make up water that is done in the basement on a 100 gal. sump tank in which is only kept 1/2 full. all work is done there. i take water from the rodi container at room temp. mix salt for 10 mins. or so, well stirred my hand to 5 gals. at a time. then i pour small amounts into the sump, then wait for the sump water temp. to recover then repeat again until goal is meet… never any regrets

  • Rusty says:

    I’ve met a few other local reefers that are big on tap water. They tell me I waste money on RODI because it removes all the “good nutrients that corals need.” Our tap water comes out at 25 dKH. I hear things like “25 dKH is great, that’s double what the salt contains. Why would you take all that out just to add back in a lesser amount?!?” My response: face palm

  • Matt says:

    Mark – Actually the old C.Brown saying seems to suit…

    Good Grief!

    I’m off to give my 200ltr RO/DI storage barrel a cuddle… 😀 Maybe I’ll eventually find me that MSWT Sweet Tea recipe 😉

  • Matt…I was expecting, “Rubbish!” or “Hogwash!”

  • Matt says:

    Terribly sorry… I erm… ah, ahem….

    Poppycock!

    Suit you sir?

  • burelle says:

    A lovely oh putain from France!

    Best terrible advice i ve read so far!

  • Evan says:

    Mark, I have 4 clownfish 3 are docile but one bullies just one of these. Anything I can do?

  • Tom says:

    I swap out my poly and sock filters once a week and I would like to soak the ones that I swapped out. Can I soak my poly filter and socks in a mixture of 1/4cup of bleach and 4 cups of water? My new poly filter is light brown within a week and I would like to get it white again.

  • bill says:

    tom .. if your not wearing those filter sock don`t worry about making them white again, it`s not like it`s your underwear, and i also heard that washing machines have a small amount of residue of phosphates in them from constant use.. i made up a short garden hose and hose off all material matter from the socks into my utility tub and then let the socks air dry until needed again, hope this helps….. bill

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