Poll: Do You Know Your TDS?

Discussion in 'Reef Aquarium Discussion' started by NY_Caveman, Jan 7, 2018.

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  1. I use tap water and I know the TDS

    8 vote(s)
    0.8%
  2. I use tap water and I do NOT know the TDS

    18 vote(s)
    1.9%
  3. I buy RO/DI or saltwater and I know the TDS

    21 vote(s)
    2.2%
  4. I buy RO/DI or saltwater and I do NOT know the TDS

    40 vote(s)
    4.2%
  5. I have an RO/DI system and I know the TDS

    763 vote(s)
    80.4%
  6. I have an RO/DI system and I do NOT know the TDS

    68 vote(s)
    7.2%
  7. I use distilled water

    10 vote(s)
    1.1%
  8. I use natural seawater

    12 vote(s)
    1.3%
  9. I really am not that worried about it

    9 vote(s)
    0.9%
  1. NY_Caveman

    NY_Caveman Troglodyte R2R Supporter R2R Excellence Award Reef Squad Build Thread Contributor

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    Do You Know Your TDS?
    I do not know if everyone tests their TDS. I do. This does not mean it is important to everyone’s system, but if it is, I am sharing my recent experiences. My primary intent is to make a recommendation to those who buy RO/DI water or saltwater from a store: if want to start with pure water, test the Total Dissolved Solids (TDS) yourself. I assume if you have your own RO/DI system in your home or business that you check it, or have meters in line, but perhaps you do not?

    Background
    First off, I am blessed with several local fish stores (LFS) near me. I live 30 minutes north of Manhattan and there are many options in New York, Connecticut and New Jersey. Most I have seen are good stores with clean tanks, beautiful corals and healthy looking fish and inverts. I have generally found staff to be quite helpful and knowledgeable.

    Additionally, in my area, we start with excellent tap water. I have lived in three cities in Westchester County and the TDS of the tap water has been between 35 and 45. NYC and the Bronx I have seen reported about the same or even lower. I have read some local water reports and could almost use my tap water directly. The big problem with that is the Phosphate level runs very high at 2-3ppm (several years of API testing).

    My Observations
    Over the past couple of weeks I have visited four of my favorite LFS nearest me to purchase RO/DI water. In each case I was surprised by the TDS level of the water. In two cases, I called before going in and was told the level was 0. One seemed surprised I asked, saying “it’s RO/DI water.”

    Here are the numbers from the four stores in ascending order:

    TDS
    7
    14
    41
    253

    Okay, 253 is nuts, but it is correct. I will talk more about that in a minute.

    Two things jumped out to me right away:

    1. if you buy RO/DI water or saltwater from a store, you should test the TDS yourself, and
    2. these LFS are likely using the same water in their own displays, and in a couple of these cases this was a little scary.

    The two lowest samples I collected, the 7 and the 14 TDS, I further tested for Phosphate. In both cases the result was barely detectable. That led me to use them as intended as change water for some dry rock I am curing. The LFS that tested 14 told me they do replace their filters every month since they go through a ton of water and I believed them. I understand that filters, membranes, resins, etc. can degrade quickly with constant use.

    The sample I got that was 41 TDS I dumped out. It was higher than my tap. I speculated at first that maybe they filled my jugs with tap. I gave them the benefit of the doubt after speaking with them. The person felt terrible and offered me store credit. Their store is pretty new and I considered maybe they had not yet changed out their filters since the initial setup. They followed up with me and noted they had replacements on order. I still wonder how long they have used it in their own system.

    The 253 TDS number was shocking and baffling. I tested multiple times while also testing other known sources to confirm. I obviously dumped this one right out. After much speculation, my best guesses are the person (a newer employee) somehow gave me the waste water from the system, or the collection containers themselves were heavily soiled. Perhaps it was some fluke or mistake. It does not really matter. The point is if I had just used it without testing I may have had issues.

    Conclusions
    I firmly believe that it is ultimately my responsibility alone whenever I add anything to an aquarium. That is why I test no matter what I am told. I urge everyone to test all pure water they purchase or make with a TDS meter.

    A good TDS meter can be purchased for $20-30 and the test is fast and easy. Just dip the probe in the water. Some areas have terrible tap water to begin with and there is only so much an RO/DI system can accomplish. In these areas it seems crucial to test.

    My research so far has shown me two things:

    1. the TDS of the RO/DI water available from local stores was regularly higher than I expected, and
    2. none of the stores themselves (to be fair the staff who helped me) knew the actual TDS of their RO/DI water and, when I asked, none knew the TDS of the tap water they started with.

    I said in the beginning of this thread, I consider all of these stores good, clean, honest and helpful. RO/DI water sales are a very small part of these operations and their system’s filters degrade over time. They probably all go through a lot of water. My point is not to bash anyone (and I do not care to name names). I only want to suggest anyone regularly buying RO/DI water or saltwater from a store should test the water themselves. If you buy saltwater, then ask them if you can test their RO/DI water or buy a small amount if you feel weird asking.

    Your Turn
    Water quality is pretty important to the life in our systems, so I felt I should share my own limited observations. What do you think? I am honestly unsure how concerned people really are with the purity of their water. These threads seem to suggest many are, but what is the reality. Do a lot of folks use tap? If you buy your water do you test the TDS level? Does the store you buy from test it? How high a TDS number is acceptable to you? If you have your own RO/DI system, do you test? How high do you let it go before swapping out filters? I would love to hear other’s thoughts and experiences. Thanks!
     
    Last edited: Jan 21, 2018
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  2. Crabs Mcjones

    Crabs Mcjones Millepora Maniac Mayor of R2R Staff Member Team R2R R2R Supporter R2R Excellence Award Partner Member 2019 R2R Secret Santa Reef Tank 365 Build Thread Contributor Article Contributor Hospitality Award

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    Good read! I have an ro/DI unit with a tds meter after the di chamber. I try as best I can to maintain 0 tds I actually picked up more di resin today as I started showing 1 tds on my meter yesterday and saw that the resin was almost completely brown lol. I use a 6 stage system consisting of a sediment filter, two carbon blocks, two 75gpd membranes, and a single 1.25lb di canister.
     
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  3. Mal11224

    Mal11224 Valuable Member R2R Supporter Partner Member 2019 Reef Tank 365 Build Thread Contributor

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    Interesting read. I see people buying water all the time and considered doing it but broke down and bought a rodi system, which pays for itself in the long run.
    I am in Long Island and my tap water ranges from 45 - 53 before it passes through my rodi and 0 at the end of it. But, I also use a manual checker to make sure it is zero. I am glad that my water starts out pretty low so it is less taxing on my rodi system.
     
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  4. NY_Caveman

    NY_Caveman Troglodyte R2R Supporter R2R Excellence Award Reef Squad Build Thread Contributor

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    Nice. How is the tap in Wisconsin? I have family there in Madison and been a few times but never tested. I have family in Michigan too and the tap is definitely not good.
     
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  5. saltyhog

    saltyhog Valuable Member R2R Supporter R2R Excellence Award Reef Squad Leader Partner Member 2019

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    My tap water TDS is 35-38, after my RO it's 0-1, and always Zero after DI.

    The TDS of 7 could have possibly been zero leaving their RO/DI. I'm amazed how much TDS can be picked up from containers.
     
  6. Crabs Mcjones

    Crabs Mcjones Millepora Maniac Mayor of R2R Staff Member Team R2R R2R Supporter R2R Excellence Award Partner Member 2019 R2R Secret Santa Reef Tank 365 Build Thread Contributor Article Contributor Hospitality Award

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    It ranges, I've gotten as low as 250 and as high as 350. And it's random. Literally could be 250 one day and 350 the next lol
     
  7. NY_Caveman

    NY_Caveman Troglodyte R2R Supporter R2R Excellence Award Reef Squad Build Thread Contributor

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  8. NY_Caveman

    NY_Caveman Troglodyte R2R Supporter R2R Excellence Award Reef Squad Build Thread Contributor

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    Good tip. I rinsed my jugs with tap as some of these jugs were new. I did not think of that.
     
    Last edited: Jan 7, 2018
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  9. skiergd011013

    skiergd011013 Well-Known Member

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    I make my own rodi and got a cheap tds meter from amazon. I test the ro water every other week or so. 0 tds
     
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  10. Crabs Mcjones

    Crabs Mcjones Millepora Maniac Mayor of R2R Staff Member Team R2R R2R Supporter R2R Excellence Award Partner Member 2019 R2R Secret Santa Reef Tank 365 Build Thread Contributor Article Contributor Hospitality Award

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    That's why the only container I rinse out with tap water is my Wastewater cuz I really don't care what chemicals or solids are in that bucket since it's not going back into the tank my other buckets I have a constant supply of RO water sitting around that I use to rinse my other buckets
     
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  11. EmdeReef

    EmdeReef Valuable Member R2R Supporter R2R Excellence Award Reef Squad

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    I’m in Nyc, recently got an Orion 130 which has been consistently showing about 2.5x more ppm than what my HM handheld shows. I haven’t gone through all the calibration as it’s showing 0 in lab grade RODI but I trust it more than the handheld.

    I’ve never been able to get 0 tds through my pretty new BRS 5 stage RO though even after changing everything but the membrane generally get 2-3 on Orion. I did an ATI test of my RODI water and It showed elevated silicone though only about 0.01ppm which Id guess is within the margin of error and I can’t bring myself to care about

    Edit: oh and I guess tap water goes from as low as 15 and into the 90s these days
     
    Last edited: Jan 7, 2018
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  12. NY_Caveman

    NY_Caveman Troglodyte R2R Supporter R2R Excellence Award Reef Squad Build Thread Contributor

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    So far in the poll it looks like everyone knows their TDS. I am not surprised, but thought it was worth asking.
     
  13. XNavyDiver

    XNavyDiver Insightful answer loading... please wait. R2R Supporter R2R Excellence Award Build Thread Contributor

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    We have very hard water down in my neck of the woods. My TDS meter has consistently measured the city water at 290 to 295. I have a six stage rodi that I mounted on the garage wall where a water softener used to be (holy mackerel was that difficult to remove! :mad:). We use our rodi quite a bit in our family as my wife uses jugs of it to fill the Kuerig coffee maker and we also use it as drinking water. My tank requires about 1.5 gallons a day in the ato container so we are probably using the rodi unit more than average. So I keep bags of fresh resin on hand to assure I'm getting 0 TDS 99.9% of the time.
    The waste water is routed to our front hedges.
     
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  14. ihavecrabs

    ihavecrabs Valuable Member R2R Supporter R2R Excellence Award Reef Squad Partner Member 2019 Build Thread Contributor Article Contributor

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    I have an RODI and get 0 TDS out from a TDS of 750-800+ going in. The one thing I will challenge everyone on here is who tests their TDS in their RO storage tank? I guarantee everyone will have a measurable TDS in their storage tank and my guess is that is what you are seeing in the LFS reading also. That's not to say that some LFS may not be very good about changing their filters on time.

    If someone wants to accurately test what the LFS is running, it would need to be a sample tanking directly from the line post DI.

    Food for thought!
     
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  15. William Henry

    William Henry Active Member Partner Member 2019 Build Thread Contributor

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    I also learned the other day that these TDS sensors can fail farily quick...Just learned that the other day. I have a sensor reading the outline on my RO/DI system and it was reading 0 when the real value was in the 20's! The sensor is less than a year old.
     
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  16. Chuk

    Chuk Active Member

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    DI water stored for any amount of time in contact with ambient air will absorb co2. That will eventually make the ph drop and creates carboxylic acid. With the zero buffering ability of DI water the ph can drop into the sub 5 range it will also increase tds as this happens.
    The only real ways to combat that is to nitrogen/ inert gas blanket your tank- no one will do that at home in ultra pure water industry we do - or you can make the water as you need it again this is a bit of a pain and potential for disaster if the top off fails. Personally, at home I keep my di water batches to about 5 gal for my top off to keep new water in there since I go through that in about 4 days.
    I have had tanks of DI water go as low as 4.0 pH when the blanketing valve failed and we didn’t catch it for a couple of weeks
     
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  17. XNavyDiver

    XNavyDiver Insightful answer loading... please wait. R2R Supporter R2R Excellence Award Build Thread Contributor

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    How would you determine if a TDS meter is giving a false reading?
     
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  18. Crabs Mcjones

    Crabs Mcjones Millepora Maniac Mayor of R2R Staff Member Team R2R R2R Supporter R2R Excellence Award Partner Member 2019 R2R Secret Santa Reef Tank 365 Build Thread Contributor Article Contributor Hospitality Award

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    That is a great question, I was kind of wondering the same thing..Is there like a calibration fluid that has a known TDS that you can use like a refractometer has a 35ppm solution to calibrate?
     
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  19. K. Steven

    K. Steven Well-Known Member R2R Supporter

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    Yes, there is TDS calibration fluid.

    https://www.bulkreefsupply.com/tds-342-calibration-solution.html
     
  20. K. Steven

    K. Steven Well-Known Member R2R Supporter

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    I have an RODI unit and know the TDS coming out of the membrane and out of the DI, but not my water source.
     
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