Salt Calculation Question

Discussion in 'Salt' started by xJamesC28, Apr 24, 2013.

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  1. xJamesC28

    xJamesC28 Bristle Worm

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    Hey guys, When I normally do water changes I just take out about 20% of my tanks water and just add some new salt water back in. If the the levels are a bit low from evaporation I will just add in more salt water to get the levels back. This is becoming a bit of a pain so I'm asking is there another, Easier way of calculating how much salt to add to your tank?
     
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  3. Corailline

    Corailline Super Moderator

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    It is a dry heat, yeah right !
    Sounds almost like your topping off with SW rather than fresh. Use your refractometer, evaporations rates are not a constant.
     
  4. Marshall O

    Marshall O Giant Squid

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    Yes, what you should do is be mixing saltwater to the same salinity as the tank water. Then replace exactly the same amount you take out. Replace any evaporated water with straight RO/DI water. No calculations needed, but the key is to stay on your top-offs (with the RO/DI water), or get an ATO.
     
  5. xJamesC28

    xJamesC28 Bristle Worm

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    Alright I see, I do top off Evaporated water with Fresh.
    I don't mix salt, I buy Drums of RO/DI Fresh and Salt water from my LFS
     
  6. Todd_Sails

    Todd_Sails Giant Squid

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    Time to get your own RO/DI- spectrapure makes probalby the best for the money system.
    And time to start buying salt and mixing your own- EASY to do, and you'll probalby get better results than what the lfs has- where you have no cotrol over the SG of the water.
     
  7. kreator

    kreator Flamingo Tongue

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    An RO/DI unit will pay for it'self in the long run
     
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  9. reefer Bob

    reefer Bob Montipora Digitata

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    An ro/di system is worth it, just out of convenience. It was the first thing I bought before my new setup. I still need to get a Tds meter.
     
  10. weems23

    weems23 Astrea Snail

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    If you know the volume of your tank fairly accurately, including water displacement from live rock, sand, coral, etc. You can calculated the grams of salt in your water based on salinity measured in ppt (g/L) or density (g/ml).

    Salt (g) = L(tank)*ppt(tank) or
    Salt(g) = density(tank) * ml(tank).

    Using the same equation you can calculate the amount of salt being removed during water change and the amount of salt needed to add to fresh water for (x) salinity. Then there is a longer equation to determine how much water of salinity (x) needs to be added to a tank to reach a target salinity, but I can't remember it now because I don't use it. Also these equations can be widely rearranged to calculate other salinity related variables, just make sure the units work out properly if you do.
     
  11. reefer Bob

    reefer Bob Montipora Digitata

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    If your using salt water to top off for evap, then you wanna obviously check your salinity. It's probably way over. But once you get it back to normal, if the fish store makes the same salinity then you just replace what ever amount you take out with salt water. Buy a refractometer to check salinty. It's cheap insurance.
     
  12. xJamesC28

    xJamesC28 Bristle Worm

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    No no no :) I use Freshwater to top off Evaporated water :)

    Thanks guys, You've helped me a lot!