Water Changes

Discussion in 'Water Parameters and Additives' started by Jaco Schoeman, 24 Feb 2010.

  1. Jaco Schoeman

    Jaco Schoeman MASA Contributor

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    We can get really technical here, but to keep it quite simple, can I get your views on the following aspect of doing water changes;

    Question:

    Is it better to replace 10% water per week, or 5% water twice a week? (total still is 10%)

    (note that all values are just examples to simplify things);)
     
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  3. butcherman

    butcherman Moderator MASA Contributor

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    technically its only a 9.75% total change
     
  4. Manic

    Manic Moderator

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    I would say 5% twice a week. Less shock for the corals and fish. Also then the corals don't need to wait a whole week for some trace elements :)
     
  5. vatso

    vatso

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    Did you calculate evaporation??? & drops lost & left over??

    This a very interesting topic! I have been asking the same question

    One must remember the water that is now only a few days old will also be removed so that does mean some "good" water will be removed.

    I myself would rather do smaller water changes but have been told it's not the best thing. I am still trying to understand why 100%

    Mark
     
  6. butcherman

    butcherman Moderator MASA Contributor

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    no if you change 5% twice a week. your changing 5% of the 1st water change when you do the 2nd whater change, but thats just technically speaking :razz:
     
  7. Singularity

    Singularity Hmmm amper!

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    It depends on what you want to do, if you want to replace trace elements with water changes i think more frequent smaller water changes is better, if you want to get rid of nutrients one big water change will be better...
     
  8. Jaco Schoeman

    Jaco Schoeman Thread Starter MASA Contributor

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    Well, my thoughts on this is as follows, but I'm not sure if I'm right.

    If I do more smaller changes, you dilute toxin more rapidly, before building up higher. Again, we can go very technical, but this is a graph I did to explain, and this is in simple terms really.

    [​IMG]

    The top shows p.p.m of what ever (PO4, Nh3Nh4, NO3 etc etc) reaching 1.75 ppm and then a water change is done.

    Second graph shows the same values, but with more frequent water changes means levels never reach 1.75 ppm

    Yes, one should take into consideration that with a 10% wc you are diluting nutrients with 10% etc etc - I know. But simply put, is it not better to do more w/c more frequently, than one large on every now and then only?
     
  9. vatso

    vatso

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    Jaco have you thought about running a massive DSB just to cycle water through? like a separate tank which you use so old water from your normal tank into DSB tank water from DSB tank back into normal tank?

    Like a water washer? then you can do water changes every day.

    just an idea not sure if it would work?
     
  10. Bob the (reef)builder

    Bob the (reef)builder

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    Its always better to do regular water changes, as it keeps a yo-yo effect from happening as much. Makes for more consistancey.

    With your heavily fed tank Jaco I think that much larger changes are likely to be neccesary.
     
  11. Neil H

    Neil H Moderator MASA Contributor

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    IMHO, one should be careful to do a WC solely as a nutrient control mechanism.... Jaco, if I am correct you have assumed that each WC reduces the nutrients (or increases trace elements) back to or up to a static point. but look at it this way...

    you have 100 units of nutrients or trace elements.
    you remove 5 through a water change and are left with 95
    next week you do not have 100, you have 195

    See why i say be carefull of using this to control nutrients in the water ..... the maths does not add up......

    I think a WC is excellent for replacing elements whose role we do not fully understand, like "trace elements"... its not like the average person understands their role or can even measure them ....
     
  12. Jaco Schoeman

    Jaco Schoeman Thread Starter MASA Contributor

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    Yes Neil, I have noted, and agree, with that. The only way to get nutrients back to the start is by doing 100% water change in one shot - and that is impossible.

    I dont think water changes must be used as the ONLY filtration method, but if I am able (on my heavily fed NPS System) to replace between 30 - 50% water per week, that has to help a bit on filtration too wouldn't you say?

    Bob, yes, I am thus planning to utilize more frequent and larger water changes per week to help me. If I do a 25% wc every 3rd day, that should help right?
     
  13. Manic

    Manic Moderator

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    That will get expensive though. Why not just utilize heavy skimming for just 6 hours a day or something. Or go the bacteria route but use only half the recommended dosage...
     
  14. Bob the (reef)builder

    Bob the (reef)builder

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    That will certainly help. By the way a 100% water change is not unheard of. Calfo does it all the time. (Maybe its 95% to allow some water left over for the fish.);)
     
  15. butcherman

    butcherman Moderator MASA Contributor

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    neil are you saying every week your tank is producing a extra 100 nutrients?
    If then surly only removing 5 nutrients and ending with 195 the following week one could conclude your WC as being to small?
     
  16. Singularity

    Singularity Hmmm amper!

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    Think he was using that as an example :p
     
  17. Jaco Schoeman

    Jaco Schoeman Thread Starter MASA Contributor

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    The values Neil used are just for mathematical simplicity.:p

    His calculation obviosly shows a 5% water change.

    Had you done a 50% water change, your 100 would become 50, and then 150, which then becomes 100 again, and then 200 etc etc.

    Your main focus is to hope that the remaining 50 in the initial "clean-up" can be taken care of by your bacteria, and other filtration.;)
     
  18. butcherman

    butcherman Moderator MASA Contributor

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    i dont think you can look at only the effects of 1 WC cause of the fact that each WC dilutes the Nutriants. Lets say there is no increse in nutrients and all we have is 100 to get rid of how many WC would it take to get rid of all 100?
     
  19. Neil H

    Neil H Moderator MASA Contributor

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    Quite correct Jaco, it was for mathematical simplicity

    and simply to illistrate the gradual increase in nutrients in our system IF was use WC as the primary source of nutrient removals

    Jaco it may be that doing larger less frequent changes would be more efffective in YOUR case.....

    Let us assume that your NPS corals have now reached a nutrient saturation point from which they will now decline in health .... if you now did a 30% WC you will be removing 30% of the water at a nutrient saturation point for your corals.... so you are effectively removing the maximum amounts of nutrients you can .... compare this to the previous 6 x 5% water changes you did where the saturation point was no where close...

    Not sure what the answer is but think about it !

    IMO as i said earlier WC should be for trace element addition in Most tanks (this excludes NPS of course due to the excessive feeding levels) SO perhaps you could look into some sort of recycling of the water ...... in a tank with some LR, and macro algae.... it would strip out the nutrients and may be usefull to use as WC water in your system ?????? Have you looked into the needs of NPS with respect to trace elements ?
     
  20. Neil H

    Neil H Moderator MASA Contributor

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    Unfortunately a tank is dynamic.... you always have food going in and fish pooping hence the addition of nutrients..... a WC is only one method of nutrient control ! So you can not assume that nutrients remain the same and WC reduce them.... only a 100% WC would reduce the nutrients to zero, and doing this would result in some die off on the LR which would immediately elevate nutrients again ......
     
  21. Jaco Schoeman

    Jaco Schoeman Thread Starter MASA Contributor

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    Yes Neil, Thank you for that. I agree fully and understand what you are saying. I think water recylcing might be something to look into... hmmmm...

    WRT trace elements and NPS, well, from what I could find, gorgonians are not AS "hungry" on trace elements.

    The Dendronephthya (Carnation Coral) has calcium spinicules in them to keep it upright and strong in heavy currents, the same with Chili Coral.

    The Suncorals, being LPS, has the same requirements as normal LPS has, so yes, those species have quite a trace element requirement. I firmly believe howeverm that if I do 30-50% wc per week, it would be sufficient replacement of trace elements, unless all the 44 suncoral babies I counted grow up into huge colonies - :whistling:

    On recylcing, I think one can take your "OLD" water, let it filter and just dose Tropic Marine Trace Elements or something. Wouldn't that work?
     
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