Over-designed salt water exchange system

Discussion in 'DIY' started by rygh, Mar 13, 2014.

  1. rygh

    rygh Supporting Member

    Well, time for a fun new project.

    I am tired of lugging buckets for salt water changes on my 240G.
    Sure .... I could just add a pump and some extra hoses ... but what is the fun in that. :p

    SO : Time to make a fully automated salt water exchange system.
    (Not a simple auto top off. This will truly drain and refill salt water automatically)

    Salt Water storage:
    A 100G tank is already on order.
    I still plan to mix the salt myself. Maybe someday that can be automated?

    Exchange plan:
    The idea is to automatically change about 15% per month.
    To do that, I will probably have it run Monday and Thursday night, at 7.5 gallons/cycle.

    Sure, I could use my current Arduino system ... but this is 2014!!!!
    Those things are antiques. And besides, the plan is to be OVER designed.
    So: The plan is to use a Raspberry Pi. Linux based system.

    Stay tuned for more details on pumps, sensors, and progress.

    I expect this project to take quite a while, like all my projects do.
    But I already started receiving some of the parts.
    Marc likes this.
  2. HiFidelity

    HiFidelity Guest

    excuse me while I subscribe to this thread real quick :D
    ok carry on...
  3. sfsuphysics

    sfsuphysics Supporting Member

    Is that what the 100g container is for? Salt water?

    And if you're thinking of automating the saltwater making process yeah... it's already over designed. Has nothing to do with lugging buckets, a pump w/ hose could work too :)
  4. rygh

    rygh Supporting Member

    Yes, 100G tank is for salt water. I want to auto-change 60 gallons a month or so,
    and I want to go a month+ without touching it.

    No current plans to automate the mixing itself. Some ideas, but not in the plan.
  5. rygh

    rygh Supporting Member

    To be clear: There are really 4 main reasons I am doing this.

    1) No more lugging buckets around.
    A big deal, but yes, certainly has simpler solutions.

    2) Even out the water changes.
    No temp/ph/chemistry swings.
    Fairly minor concern though, unless I really increase the amount of changes.

    3) Because I procrastinate and forget.
    This is really a big deal. With work + all of the kid's activities, I keep postponing
    water changes until tomorrow. And all of a sudden another month went by.

    4) For fun.
    The most important reason. :)
  6. Marc

    Marc Guest

    Wheres the subscribe button!?!
  7. sfsuphysics

    sfsuphysics Supporting Member

    Well reason #4 is all you really need :D

    So you'll have automated changing, but presumably you'll still manually make the water. Also have to have some sort of periodic movement of water inside the container won't you? Otherwise won't stuff settle? I'm not sure what stagnant salt water will do after 2 weeks.

    My container is going to be freshwater, and I'll just mix salt water as I need it, I was going to go with 2, one fresh one salt but decided against that at the last moment as I didn't want to have to deal with any sort of plumbing/pump solutions at this time. Also worried about "stale" water. I'm putting "ultra-pure" water into the container, presumably bacterial growth could run absolutely rampant in there since any disinfectents have been removed via RO/DI, obviously won't want to drink that water but need to maybe research that aspect a bit more.
  8. rygh

    rygh Supporting Member

    At the top of the thread on right.
  9. rygh

    rygh Supporting Member

    Circulating water in the big salt water tank is an issue, yes.
    Simplest solution is to put a small power head in there.
    Another option is to use the pump that transfers water out to reef system.
    Basically oversize that, and have most of the water return to storage tank, and only a small percentage
    go to the reef system. Not a bad option since I have some extra pumps.
    Depends on the type of pump though.
  10. rygh

    rygh Supporting Member

    There is nothing to kill the bacteria, but then there is nothing for the bacteria to eat either.
    I have never noticed much bacteria in my fresh water barrel. Seems like less than inside your
    typical biking water bottle.
    Plus, any bacteria in there would likely be pretty natural, not from human waste, so low risk.
  11. sfsuphysics

    sfsuphysics Supporting Member

    Well two options (technically 3) I can think of
    1) Pump that plumbs into bottom of container, teed off so one goes up and back in, another to the tank, the tank side has an PVC electronic solenoid valve (normally closed until your controller tells it to open)
    1b) Same idea, but two solenoids so there's wiggle room for how much water flows out of your pump (but more pricy)
    2) Cheaper alternative, use two pumps on a Tee that leaves the bottom, one end of the tee plumbs from your pump back to the storage tank, the other pump only turns on periodically when you want to do your auto change. A DC pump would work nice here since they tend to be set up to "slow start"
  12. rygh

    rygh Supporting Member

    I think my preference is to run the salt water mixer 24/7.
    As opposed to turning on a mixing pump an hour or two before pumping water out.
    The reason is that once it settles, it can form pretty solid deposits.

    Given that, the big problem becomes power usage.
    So a small propeller based powerhead at the bottom is probably best.
    Perhaps a Hydor Nano 425 GPH at only 3.5 watts.
  13. HiFidelity

    HiFidelity Guest

    I would start with automating the salt water mixing since that would be ultimate and everything from there is basic.

    I would imagine that this can be done utilizing the following tools;

    Salt Mix container with the opening on the bottom connected to a gate valve or solenoid preferably 12 vdc connected to a relay.

    ATO dedicated to the SW reservoir

    Pumps + sensors to monitor and tap into your sump

    FW reservoir feeding ATO that goes into SW reservoir

    Reef Angel w/ salinity probe & some custom code

    The harder part;

    A. automate water changes on a time table, ie; remove 5 gal twice a week (just an example) or every few hours so your SW does not settle and replace with new SW from reservoir.

    B. Reservoir auto refills SW mix & FW until desired salinity is reached (very dependent on how flexible a Reef Angel's programming can be)

    C. FW reservoir auto fills from RO/DI

    D. LOG of SW volume removed, SW volume added, etc.

    So basically it comes down to whether the RA can be programmed to do this or not and I would imagine it would be the most readily available piece of electronics that could do this if in fact it is programmable to this extent considering that it already has Salinity Probe capability.

    The SW mix reservoir can basically be an upside down water cooler jug (5 gal) onto which you can rig the gate or solenoid where you can time the intervals of when it stays open thus controlling the amount of SW mix you are adding...

    A Salinity Probe is essentially a conductivity meter so you can still do this with Raspberry if you don't want to go the RA route. In that scenario the Raspberry would be dedicated strictly to the automation of your water changes and stay independent of your DT controller and so on.

    I don't know, am I onto any feasible track here or is this impossible nonsense? lol before I go off on a tangent...
    Last edited: Mar 13, 2014
  14. rygh

    rygh Supporting Member

    Hmm... add salt mixing huh...

    The reef angel components are I2C based, so I could use that probe with the Raspi.

    I would need some sort of auger powder dispenser type mechanism for dry salt.
    Pretty sure a simple solenoid would jamb quickly.

    Reef Angel programming is 100% flexible. You get the source code, and can do whatever you want.
    I used to use one.
    Logically probably a better solution .... but not as FUN.
  15. rygh

    rygh Supporting Member

    Quick drawing of sump connections
  16. HiFidelity

    HiFidelity Guest

    I'm wondering if an auto feeder can be hacked up to a bigger container, I know salt mix likes to clump but when kept dry it flows pretty much like table salt which certainly does not clog against a small opening when kept dry...

    There are controllable feeders out there that might make candidates for this.
  17. rygh

    rygh Supporting Member

    I looked at industrial items, like hot chocolate and fertilizer dispensers. Most use auger type drives.

    Seems like a simple auger wood bit, in a PVC pipe, and tied to a used fridge ice machine motor
    might do the trick well.

    Or just buy a used hot chocolate dispenser.

    The pet food ones are mostly gravity based, meant for pellets, not powders.
  18. rygh

    rygh Supporting Member

    The Raspberry Pi
  19. rygh

    rygh Supporting Member

    Display is working. Simple 2 line LCD. Solider-it-yourself kit.
    Although hooking a full monitor to it is easy.
    Also I have GPIOs toggling some leds ..... based on how many unread emails I have. Pretty fun.
  20. HiFidelity

    HiFidelity Guest

    you have much more of this already figured out than I first anticipated :D

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