The Whole Water Change Thing

Discussion in 'Water Chemistry' started by ReefSparky, May 22, 2008.

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  1. bioreefdude

    bioreefdude Fu Manchu Lion Fish

    Apr 24, 2009
    stockton ca
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  3. Night-Rida

    Night-Rida Finback Whale

    Jul 3, 2009
    Tampa, FL
    Well today I found out my nitrates werent at 0, for the last 6 months as I thought. they are at 100! so went home to see my api testing kit, I wasnt doing the darn thing right and waiting 5mins for results. So I did a 20% WC and tested 1 hour later and it dropped to 40-50 range.. now 6hrs later it when back up to 80-90 why??? I guess its time for a few more WC in next couple days...aarghh
  4. bje

    bje Long-fin Bannerfish

    Apr 12, 2009
    probably a better suited question for a new topic... you probably have some form of nitrate factory somewhere if you did a 20% change and went from 100ppm to 50ppm and then 6 hours later you're back up around 100...
  5. ReefSparky

    ReefSparky Super Moderator Staff Member

    Nov 27, 2007
    South Florida
    That is true. One thing--if you have a very efficient skimmer, you should know that the salinity of skimmate removed at least equals the salinity of your tank, so over time, you'll see a decrease in salinity of your tank water. This is especially true if you're emptying large amounts of skimmate regularly. ;)

    But to reiterate the above, yes--topping off is done with RO/DI (or just fresh) water. Water changes are performed with salt water. The salinity of that water is equal to the tank, or slightly or higher or lower, depending on your need to raise or decrease total tank salinity.

    Old thread, I know, and I learned a lot from it. As we all usually find what works for us and stick with it, I developed a habit of once-monthly, 15% water changes.
    1 person likes this.
  6. Screwtape

    Screwtape Tonozukai Fairy Wrasse

    Sep 25, 2008
    That reminds me. One other thing that affects salinity slowly is using 2-part dosing. You will end up with a buildup of extra sodium chloride (byproducts from the sodium bicarbonate/carbonate and calcium and magnesium chlorides) over time that will raise your salinity over the course of weeks/months. How fast depends how much you need to dose to maintain your chemistry. Something to keep in mind and keep an eye on.