Micro Top-off Reservoir

Discussion in 'DIY' started by pixelpixi, Jan 10, 2016.

  1. pixelpixi

    pixelpixi Guest

    Today I was looking at my cramped aquarium closet and realized that I really have no need for a large top-off reservoir. The old reservoir was a 3 gallon bucket and just took up too much space, so out it went!

    I decided to make a new one that's much, much smaller. In fact, it's smaller than a shoebox-- just big enough for a float valve and a tunze osmolator pump!


    I'm loving this new setup so far. It provides the safety benefits of my old setup (DI filter is not connected directly to the sump, so a failure won't flood the tank with freshwater) but it requires way less space. I'm considering building a new sump soon and may build this into it near the back, with an added safety overflow outlet that drains somewhere safe.

    By the way, for years I've used a sediment filter, carbon block, and DI resin but not RO. With our excellent water quality here I've always found that DI does a great job and lasts plenty long by itself. RO just isn't worth the hassle for me. Curious if others do the same thing?
    wpeterson likes this.
  2. zeroinverse

    zeroinverse Guest

    I still need to do an automated top-off reservoir. I like your method.

    Where do you live again?
    In Walnut Creek, TDS was in the 40s. In Berkeley it is pretty low. I have heard in South Bay it is very high.

    I rodi'd in Walnut Creek, have not in Berkeley, and if I lived in South Bay, I'd probably be crazy not to filter.

    That said, I am debating running DI only into a topoff reservoir. Thanks for idea.
  3. Enderturtle

    Enderturtle Volunteer

    In the south bay much of your water is coming from ground water which is replenished by ponds/local reservoirs in the bay area.

    Peninsula people (and any other city that gets SF Water) get a lot of their water from crystal clear Hetch Hetchy Reservoir in the sierra nevada mountains, as opposed to those mercury filled/motor boat driven/sediment filled south bay area reservoirs. You've also got potential bad pipelines, mercury, and other contaminants to consider. You can always call your water company to ask about your water source and what goes in it.


    At first I thought, shoe box size reservoir? That holds nothing! But then I realize this reservoir is being topped off by an RO/DI unit? That's pretty cool. So when the float switch is trigger it turns the RO/DI unit on? How does that work? I have an RO/DI unit but I only turn it on when making water.
  4. pixelpixi

    pixelpixi Guest

    I'm in Point Richmond, so my water comes from EBMUD. Incoming TDS right now is 61. Interesting to hear about the differences around the bay. I knew SF also has great water quality from Hetch Hetchy, but I didn't realize the south bay was so different. Of course, DI-only would work anywhere, but if TDS levels are 10x higher then the DI resin will get exhausted 10x faster.

    @Enderturtle: The DI filter is on at all times and is connected directly to the float valve, so it keeps that little reservoir full. Since there's no RO stage I don't have to deal with wastewater and turning on/off frequently isn't a big deal.
  5. Vhuang168

    Vhuang168 Guest

    TDS of 61! Lucky! My tap TDS is 350+!

    Sent from my iPhone using Tapatalk
  6. pixelpixi

    pixelpixi Guest

    Where do you live and what water district are you in, @Vhuang168?
  7. Vhuang168

    Vhuang168 Guest

    San Jose. Water is from SJW.

    Sent from my iPhone using Tapatalk
  8. Flagg37

    Flagg37 Officer at large

    Yeah, I'm near by you. I have great oaks water though. The highest I've tested it at is 423.
  9. tygunn

    tygunn Webmaster

    I'm in Cupertino and average 280TDS out of the tap. VERY hard water; it took a while to figure the right junk to put in the dishwasher to remove the hard water deposits.

    So you have the float valve directly connected to your water source? Makes sense; very unlikely the valve will foul due to a snail or whatnot. If you were running an RO system I'd suggest what I had done in the past with a similar top off reservoir; I fed the float valve with a solenoid that I put on a timer. I basically had it come on for 5 minutes every few days so that I was using larger batches of water and avoiding TDS creep. Also acted as a bit of a backup "just in case" the valve stuck open.
  10. pixelpixi

    pixelpixi Guest

    Yeah I've considered using a solenoid/timer to limit overflows in case of a float valve failure, but I'm unsure how much more reliable the solenoid would be than the float valve. Probably some? Maybe a lot? Not sure. I have the same issue with my saltwater mixing tank (still in the aformentioned closet) which is also hooked up directly to the DI output.

    I've also thought about adding a float switch to the reservoir and setting it up to text me if the float switch gets triggered. Or just an emergency overflow outlet above the normal water level that drains somewhere safer (like outside or into the crawlspace).
  11. tygunn

    tygunn Webmaster

    Yes, valid point. I mean, I got by for 3 years using a float valve top off from my RO/DI system, directly in the sump of my 140g tank. Lol. So even the simplest solutions can on occasion work. I imagine just detecting the leak and ensuring it can drain somewhere safe is probably a reasonable approach.

    This is part of why I keep dreaming of doing an outdoor tank when I get a house; all the mess outside on a patio where I can hose it down and not ruin my house.
  12. rygh

    rygh Supporting Member

    There is another downside to a float valve controlled RODI.
    The RODI is only on for a short time. It only fills the small amount you just pulled
    out with the ATO.
    Doing that means it is not really flushing properly, in theory leading to much shorter membrane life.
    (Somewhere on RC there was a big long discussion on that)

    Also: Do you have the back-pressure valve that shuts off input as well?
    Otherwise you continuously waste water.

    I still use a float valve myself, but semi-manual. I turn the main line on for a day every few weeks.
    Part of my big rev-2 change is to switch to a simple solenoid.
  13. zeroinverse

    zeroinverse Guest

    @rygh, pixel is only running DI.

    But yes, for RODI, it is best to have one of those shutoff valves. I find they take a while to fully turn off, since they are pressure/membrane based devices.

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