Sort of considering the Genesis Reef Systems auto-water change device

Discussion in 'Equipment' started by Vincerama2, Feb 28, 2017.

  1. rygh

    rygh Supporting Member

    An ATO sensor error will not cause "drift" over time.
    If you fill it a bit too little one time due to sensor, the next time it will automatically fill a bit more.
    That little-less/little-more cancels out.

    But that is not true of water exchange. Each time the sensor is off a bit, salinity stays off by that bit.
    Largely because the next time it is used will be for ATO, not salt.

    If your sump is 2' x 2', a small 1/16" error is 0.15 gallons.
     
    Last edited: Mar 1, 2017
  2. Flagg37

    Flagg37 Officer at large

    My sump is 28"x28" so pretty close to your example but the chaimber where the ato is is only 6"x10".
     
  3. Vhuang168

    Vhuang168 Supporting Member

    While that is true, there are so many other ways salt is lost. Skimmate, salt creep, testing, dipping corals etc. In a 200g system, how significant is a +/- 0.15g of saltwater difference?
     
  4. rygh

    rygh Supporting Member

    It depends on the size of the water transfer per cycle.
    I run 48 small cycles per day, each about 0.02 gallons.
    Since the possible error is 7 times larger than the cycle itself, that is a huge issue.
    If I did one 30G change per month automatically, then it would not matter at all.
     
  5. roostertech

    roostertech reef noob

    Why many small doses and not just one gal in one shot? Even if the time it take to pump out 1g will trigger your ato, in the end it won't matter.
     
  6. rygh

    rygh Supporting Member

    1) Most peristaltic pumps are not rated for 100% duty cycle. And the ones we get are not even rated at all. Long pump times can damage them.
    2) I often spend an hour or two in the garage, and it will cycle for a bit when I am in there. Good to see it happen.
     
  7. Vincerama2

    Vincerama2 Evil Overlord

    This is too complicated. Buckets, hoses and towels it is!
     
  8. Flagg37

    Flagg37 Officer at large

    Isn't that an argument to use a regular pump and do fewer larger WCs? Like you said if you did one a month or even one a week, the difference in volume due to inaccuracies would be minimal.

    It's my opinion that doing more smaller WCs will yield more stability but at the sacrifice of more new SW. Fewer larger changes are more efficient but cause greater swings in levels. There is a balance which is different for each tank and even will change over time as the tank changes.
     
  9. rygh

    rygh Supporting Member

    I think is one of those cases about comparing too many things at once. :)

    Agree: A single large WC per month would work with a regular pump and a float switch.
    (Note, you don't entirely need the bottom float switch, just pump out for a set time)

    Side note:
    I might recommend a Diaphragm pump over a Magnetic drive pump if you go that way.
    It allows for some self priming, has way better head pressure, and is a bit more reliable.
    Magnetic drive pumps can lock up when sitting idle for a month in our tanks.
     

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