Source Water, testing

Discussion in 'General Reef Aquarium Discussion' started by saintsreturn, Jun 13, 2018.

  1. saintsreturn

    saintsreturn Well-Known Member

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    Good Day Everyone!

    We talk a lot about testing our water and ensuring our RODI units are producing water with 0 TDS. After researching solutions to my algae issue, so many responses came back to "check your source water."

    So for me, and any others out there, I would like to ask what that means? I have a TDS meter on my RODI and i just ordered a stand alone unit to provide secondary results. But what else should I be testing for?

    I am going to leave all other parts of this conversation out, such as; feeding, lights, bio load, SW parameters, etc...

    What do you do to ensure your RODI is producing the best water possible? Do you run tests outside of TDS?

    Thank you all for your answers and time,

    Logan, aka Saint
     
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  2. DaveK

    DaveK Well-Known Member

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    TDS is about all you need with testing RO/DI water. If there is noting in it, your not going to have any other problems. However if your in doubt you can test the RO/DI water for nitrates and phosphates, as these are the two main sources of problems with tap water. Also silica is often not completely removed by RO alone, and needs the DI section to fully remove it.

    On my own system I expect to see about 170 ppm TDS from my tap water and about 4 or 5 ppm TDS out of the RO unit and under 1 out of the DI unit. If I see the TDS reading from the RO unit rise I know it's time to change the resin in it.

    One final note. Testing pH in RO/DI water often gives incorrect results, because there is nothing in the water. You can safely ignore these reading, especially if done with a pH meter. Some people really get bothered by this, so if you are one of them, you can adjust the pH with a small amount of baking soda. Since this adds something to the water and there is nothing there, you only need a couple of teaspoons of baking soda per 50 gal to get the pH up. With a 0 TDS to start with you have no buffering, and that's why that small amount of baking soda can shif the pH so easily.
     
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  3. Pat24601

    Pat24601 Well-Known Member

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    When I say things like that, I just mean TDS.
     
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  4. saintsreturn

    saintsreturn Well-Known Member

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    Thank you both. I will test the water tonight with the new external TDS meter and see what it says and may pickup some baking soda, even though i have literally never messed with my RODI water before. Just trying to eliminate all possibilities before i dump more money in my system.
     
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  5. Uncle99

    Uncle99 Well-Known Member

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    What a great question, DaveK is right on point.

    What I have been testing for about 6 months now is what happens to Zero TDS water that is stored.

    The answer surprised me. I started with 20 gallons of RODI water which had a TDS of 0. I put on the air tight cover.
    The next day TDS was 2, by weeks end 7, and by months end 28.

    No a clue how this happens but maybe the airtight lid is no so air tight.

    So what was happening was the first weeks water change was TDS 2, but subsequent 3 weekly changes was putting back higher TDS. Does this matter. I am thinking not immediately but does it build up over time.

    So 3 months ago now I made some changes to combat this TDS increase.

    1.-I make only enough RODI for the weekly change + weekly ATO.
    2.-I make RODI on Friday, mix in Salt Saturday, use it all Sunday.
    3.-I rinse buckets with a hose, towel dry, turn upside down until the next week.

    Wow, after only about 4-5 weekly changes, I noticed the following:
    1.-even the small algae patches disappeared.
    2.-glass cleaning went from 2 per week to 1.
    3.-small cyno patches gone completely.
    4.-sand turned white and stayed that way.

    My conclusion (which of course is an opinion) is that making and storing RODI leads to higher TDS over time and this higher TDS gets in your tank.
    In addition, I noticed over time if I stored saltwater, I would end up with a brownish haze on the bucket walls. People tell me it's an "anti caking agent" and is harmless.

    Just in case, I rinse this bucket after each weekly mix, cause I don't want cake in my DT.

    Just my two cents, some say small TDS fluctuations doesn't matter, too much work, but since implementing the results have been quite notable
     
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  6. Squatch XXL

    Squatch XXL Well-Known Member

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    I have a theory on this:

    Water is a solvent. RODI water is as pure as we will get in the hobby. By nature, water does not like being in this state. IF the container you are putting it in is sealed, and you are consistent in your test methods, I would think that your container is leeching into the water. Plastics have a way of absorbing things over their lifetime, and I would imagine that RODI could pull the materials back out.

    New plastic containers are notorious for having some sort of oil on them from new....especially 5 gallon buckets from home improvement places....but it seems that IF a container "nests" inside of another, they use this oil to make them easier to separate. This is all trash cans and 5 gallon buckets. I am SURE there is a way to suck most of the chemicals from the surface/subsurface but you will probably never be able to get them totally clean/clear.

    IF you are not mixing salt when you make it, another more costly and absurd option would be large airtight glass lined tanks.

    I am curious about the type of container you are using, and its history. Food/pharmaceutical grade plastics may not have these issues, or the issues may be less.


    Again, just an opinion. I test my water a few times a decade, but I work in an industry that regularly handles RODI and other more toxic chemicals. RODI is nasty. Sure it is water, and we don't think much of it because we drink water and use it all the time, but the properties of it are quite interesting. Water wants and needs to reach a balance point. Water is a magical thing. Changing one property causes it to act totally different then expected.



    I would say that it sounds more like the beginnings of bacteria. I douse vinegar in small amounts via my top off tub. In order to keep the vinegar from causing bacteria in the top off, I have to keep the PH very hard. I conveniently also keep Kalk in my top off...My top off water is in no way safe for life (ph is no where near neutral), so nothing ever grows. I have had issues in the past where my vinegar containers would get scuzzed up with what looked like penicillin growing on the surface. Eventually I gave up and just added it directly to the kalk. I could be doing it wrong, but I do everything wrong, and my tank has never looked better. I don't even use RO-DI as I have a well, and am ok with the bit of silica.

    *Edit*
    I found this article, and learned some things from it right now. Some things can be dissolved in water, but never show on a TDS meter.
    http://www.reefkeeping.com/issues/2004-04/rhf/feature/index.php
     
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    Last edited: Jun 16, 2018
  7. Uncle99

    Uncle99 Well-Known Member

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    I like your thinking.
    Just using the standard brute garbage can, rinsed and dried after each use to prevent build up on the sides.
     
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