A Near Perfect Auto TopOff System

Discussion in 'General Reef Topics' started by ReefSparky, Dec 3, 2009.

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  1. Peredhil

    Peredhil Giant Squid

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    Good write up Sparky!

    I agree that an ATO does not have to be an accident waiting to happen.

    Mine is hooked up like this.

    RO/DI (with the ASOV) is hooked up to this (which is in my ATO reservoir)

    Level-Loc auto top off unit for RO systems - English

    This thing has a solenoid as RS described only allowing it to work when it has power. No power, no flow.

    Additionally, this thing has a normal float valve. But if that fails, there is a secondary float that sits above the water. So IF the main one fails or if the solenoid fails, the secondary float will catch it. Since this one is out of the water, it won't get gunked up. Worse case scenario is my reservoir gets a gallon or two too much water in it. But it's a 20 gallon tub with only 3 or 4 gallons in it. So no harm.

    If you're wondering, I only keep 3 gallons for 2 reasons. 1. Less likely to flood my tank. 2. Too shallow for my baby girl to somehow get the lid off and fall in and drown. She's bigger now, so less of a concern (she'll be 2 next month), but when I first set it up she was just starting to walk around with confidence.

    Also, this thing is plugged into a timer. I have it set to run one hour every day. Because it's in a reservoir and not hooked to my system, I don't need to worry about doing it twice a day or whatever to maintain SG. Not relevant. So if all else fails, it can only run for one hour a day.

    So far, so good.

    I have this for my DT.

    TUNZE Osmolator Universal 3155 - English

    It maintains proper levels using a laser (that is so rad) and has a back up float, so in the event the laser fails (or is blocked by coralline or a snail) and the ATO starts pumping too much water, the backup float will stop the flow.

    One time, a snail got under the float which caused the whole system to shut down... kind of fail safe/snail safe ;)

    It also caused an alarm to sound. Took me a minute to figure out it was a snail...

    If I have power failure, no water will get pumped. If for some weird reason both sensors fail in such a way the ATO thinks it needs to add water, at worse, it will be able to fill only as much water as in my reservoir (3-4 gallons). That can be fixed with a single water change. Although a failure is, by far, more likely to cause no water to run...


    So many things would have to fail at once for this to cause any serious issue for me... It is probably 98% fail proof.

    It uses basically RS recommendations but has an extra layer of protection by using a reservoir (IMO).


    I use to manually use buckets. IMO, it is far easier to mess up your SG with buckets than it is with a well setup ATO system.


    Now granted, the level-loc + Tunze is about $300 bucks. But to me, it is so worth it. I can go on vacation, I can not worry about lugging buckets. SG is constant with 0 fluctuation through the day.
     
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  3. steve wright

    steve wright Super Moderator

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    Excellent and entertaining write up Reef Sparky

    lottery wins, lightning strikes, Vegas and an ATO
    you losing 3 gallons per day through evaporation , thats about 2.5 gallons more than I lose on my tank most days

    Steve
     
  4. ReefSparky

    ReefSparky Super Moderator

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    thanks, hydrojeff. :)

    Thanks, Steve. :)
     
  5. CoralCrazy

    CoralCrazy Spaghetti Worm

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    Very nice write up, have been looking at DIY topoffs for a while now so this definately helped.
     
  6. unclejed

    unclejed Whip-Lash Squid

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    Hey sparky, so are you saying that 30 min. of fresh water entering the tank if the shut off fails won't harm anything? Maybe in a huge system but not 55 gal. or less.
     
  7. ReefSparky

    ReefSparky Super Moderator

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    Hey Jed. My 90 needs about 3 gallons per day. My RO/DI produces 5 gallons in 72 minutes, so 30 minutes yields about 2.5 gallons or therabouts.

    30 minutes of fresh water entering the tank will give the tank about what it needs in any 24 hour period. Mind you, that would only happen if the float valve were to fail. If it did, the solenoid would shut flow off after the 30 min's.
     
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  9. GoToSleep

    GoToSleep Torch Coral

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    The pumps typically used with these ATO systems don’t move water very quickly. I think that my Tunze osmolator might only pump a few quarts over 30 minutes. Obviously, add a couple extra quarts of fresh water to a small tank might not be ideal but the timer should be able to prevent a catastrophic drop in salinity (and a flood) in the event that the first two safety mechanisms fail.



    There is a challenge that remains even with redundant systems and that is the possibility that the first line of defense might fail and go unrecognized because we are complacent about having a system with 2 or three fail safes. If you are not vigilant and detail oriented when checking your system each day (or week, or month) you might go quite a while with a failure at one of your safety levels. This ups the risk that you could have a second level of defense fail while the first level is already out of commission. This is an interesting challenge that I face as I get my system more and more automated. There are fewer mundane daily activities that I need to attend to but there are a lot more subtle details and places where things can go wrong.
     
  10. ReefSparky

    ReefSparky Super Moderator

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    You make a good observation. To have 2 float valves monitoring one reservior would be necessarily complex in that it would require either both float valves to be mounted at exactly the same height (no circuitry, wires, or electricity involved) or there would be one "high level" valve, and one "high high valve" which would require wires, circuitry, and to do it right; would utilize device addressing and incorporate software. If you took this route, then you might as well buy one of the excellent computer-controlled ATO's available on the market. However, in my analog control loop world, I'm limited to one float valve; and I'm comfortable with my risk.

    I like the comments this thread has generated. It makes me think even more about the distinction between simple and complex. They both have their pros and cons. A simple system like mine lacks multiple redundant fail-safes, but happily cuts down on potential points of failure, not to mention that IMO, it's "good enough," while costing pennies in comparison to the marketed systems for sale. A sophisticated system with multiple safeguards would protect against flooding very well; but if and only if all components are in working order. They cost a pretty penny, and IMO leave many variables out of the user's control. Personally, I'm not a fan of variables.

    I feel secure enough with my inexpensive, unsophisticated system.
     
  11. unclejed

    unclejed Whip-Lash Squid

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    Yes, I see. My 55 gal. only requires 1/2 gal. a day so if the float stuck it would receive 2.5 gal. I am not sure what effect that would have.
     
  12. Peredhil

    Peredhil Giant Squid

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    http://www.3reef.com/forums/general-reef-topics/peredhils-mistake-71391.html

    I'm sure. Due to an unfortunate mistake on my part in the past - I was siphoning out my skimmer (HOB) but forgot to break siphon. Long story short, I pumped ~4 gallons of fresh water into my 55.

    Anyway, in 30 minutes (how long it took my Tunze to pump 4 gallons) my SG dropped from 1.027 to 1.024. I had simultaneously pumped out 5 gallons of SW. So this is a bit more than simply adding 4 gallons of fresh. I was kind of replacing SW w/ FW.

    So if I hadn't been pulling water out, it probably would have dropped to only 1.025 or so.

    One water change and I was back in business. But I didn't go that route. Instead I just topped off with SW for a few days. no big deal.

    But those pumps can pump more than folks are thinking apparently.