Returning to the world of salt... and have a question

[FishWife]

Hi, all!

 

Greetings from WV! I used to live in the DC area and had a wonderful 180 bowfront that so many of you who were here 10 years ago helped me with. It was a sad day when I had to part it all out and go a-wandering. I've had a freshie 110  (rainbowfish) for the last two years, but am getting the itch to re-up a reef tank.

 

Here's my biggest obstacle, as I see it. We now live on a 40-acre farm in rural WV mountains. I can't see a neighbor; people around me raise cows and I raise chickens. I love it here, and it's my permanent (earthly) home. I mean it: we are going to be buried on the property someday. But I digress.

 

We have spring water. What parameters do I need to check/correct for using spring water?

I know copper is right out; will test for it.

The water is calcified, which I see as a good thing, right? Saves me from needing a CA reactor? KH is 161 ppm and GH is 179 ppm.

What about nitrates? They tested today at 10 ppm. If that's a problem, can I correct for them? How? RO/DI?

Our water pH is around 7.5-8 out of the tap. 

 

Thanks in advance for your help... not sure why the gray txt background... sorry!

 

 

[Origami]

Hi Marcia! Welcome back! Wow, it's been a long time.

 

When you say spring water, do you mean well water? I have several springs on my property here in zcentral Loudoun, but we draw water from a well.

 

The calcium in your water is a component of conventional water hardness. It's present along with magnesium to a lesser extent and carbonates. However, along with that, you can get stuff that you don't want: Copper and other metals, sulfides, nitrates, and other stuff.

 

Most of the time, we in the hobby process our water thru RO/DI systems to remove all this stuff. This basically takes our after back to a known purity (0 TDS) so that what we add is what we get.

 

Unfortunately, for those of us on wells, our water can also have elevated levels of carbon dioxide that, when pushed thru RO/DI stages, can very rapidly exhaust the DI resin stage. Actually, dissolved carbon dioxide forms a negatively charged ion that exhaust the Anion resin. But, because it results in a color change in the mixed bed most typically used, we Ted to think of the whole resin stage as being exhausted and we replace it (even though the cation resin is probably largely still good). All this replacing adds up, makings it expensive to operate. My water comes up with high dissolved CO2, so I suffered "exhausted" resin after making as little as 100 gallons of water. I needed a different solution.

 

So, I sent in samples of my well water for ICP testing and determined that my water was fairly clean, but that it also had a few positively charged metal ions that I wanted to remove. I decided to do this by separating my mixed bed resin and replacing it with two stages of cation resin to go after the positive charged metals (which were still very low, but still something I wanted go after.

 

Anyway, long story just to say, "get yourself an ICP test from somebody like SaltwaterAquarium.com and send in a freshwater sample for analysis so you know what you're dealing with. ICP is more appropriate in this case than standard well water tests, so I recommend that approach.

 

Again, welcome back!

 

Sent from my tablet using Tapatalk

[FishWife]

Thanks for the warm welcome, Tom, and great information.

 

Our water source is a true spring: it comes up through the ground into a spring box, and runs all year long. Great tasting water! My initial concern with a reef was nitrates. We have a household water softener system that the water passes thru before hitting our sinks. Uses Sun Salt. I've been using our water straight from the tap for 2 years with a 125 that has rainbow fish in it. (I chose rainbows specifically because of the water parameters so that I wouldn't have a lot of water chemistry to deal with. They are also pretty, active, and fun to keep. I don't want to take down this tank, but am looking to add another.)  My point here is this: during this 2-year interval keeping freshies, I've had snails doing fine... would freshie snails tolerate copper and other TDS better than our marine creatures? Hmmmm.

 

So, this testing is new to me. Got some questions for ya:

 

1) Am I looking for those elevated CO2 levels when I do this test? 'Cause I think I have them, because when I let a test tube of water sit overnight, the pH falls almost a point.

 

2) Does RO/DI take Na out? Because, hypothetically, if my water is clean enough of TDS, I'd still have the nitrates to deal with. If that's the case, could I pre-process the fresh water biologically... I dunno, like with an algae scrubber or other filter media like biopellets... and then add salt and use it, bypassing the hassle with RO/DI resins?

 

3) Reading the description of the test, they are talking about sending aquarium samples of SALT water... can I send fresh and have good results?

 

This has got to be my first step in returning to reefing. I need to get clear how I'm going to source water. (Duh, I know.) THANKS for any help on this!

Edited August 31, 2018 by FishWife

[treesprite]

Hey Marcia, good to see you!

[madweazl]

If the pH is dropping over time, I'd think CO2 levels in the home to be the cause vice the water. 

 

RO/DI units are effective at removing most nitrates.

 

Some providers of ICP test your fresh and saltwater (e.g. ATI ICP). 

 

As Tom had stated, a four or five chamber RO/DI unit will allow you to run separate anion and cation resin (or multiples of either) so you're only replacing what is exhausted. I believe RO/DI units are one of the best investments you can make. 

[FishWife]

Thanks!

[Origami]

 

1) Am I looking for those elevated CO2 levels when I do this test? 'Cause I think I have them, because when I let a test tube of water sit overnight, the pH falls almost a point.

 

2) Does RO/DI take Na out? Because, hypothetically, if my water is clean enough of TDS, I'd still have the nitrates to deal with. If that's the case, could I pre-process the fresh water biologically... I dunno, like with an algae scrubber or other filter media like biopellets... and then add salt and use it, bypassing the hassle with RO/DI resins?

 

3) Reading the description of the test, they are talking about sending aquarium samples of SALT water... can I send fresh and have good results?

 

This has got to be my first step in returning to reefing. I need to get clear how I'm going to source water. (Duh, I know.) THANKS for any help on this!

 

Spring water may have different factors to consider (e.g. coliform bacteria). However, elevated CO2 may be mitigated as the water has already had a chance to blow off. If you're seeing pH actually DROPPING a point when sitting overnight, then it's likely because CO2 is being added from the air inside your house (where CO2 concentration is typically higher). Dissolving CO2 into water makes it more acidic - that is, pH drops. It sounds like dissolved CO2 should be less of a concern in your case. If that's true, then you should be able to use a standard RO/DI system to clean up your water.

 

Yes, an RO/DI system will remove dissolved sodium (Na). It'll remove just about all solids and dissolved solids through the filters, membrane, and resin stages. If you have a water softener, any calcium and magnesium is largely being replaced by sodium anyways from the water softener salt. (I installed a water softener at home last year, too.)

 

In your case, I'd consider getting an RO/DI system rather than running with straight spring water. At least you'll know your water quality is not varying because you'll be stripping it back to a known state. You may want to periodically test the water anyways with a home well test kit (including the coliform test) and maybe an ICP test just to get a better understanding of the water you have there. (I do a home-test of my well water every 12-24 months using test kits that I can pick up at Lowes.)

 

Edit: On Q3: Yes, I asked that same question of ATI. I selected their ICP test kit because a) It provides two vials - one for your fresh water and one for salt. They give you ICP results for each. They don't test the one in the fresh water vial for total alkalinity but both vials go through the ICP machine. You can, for example, put your spigot water (assuming it's before your water softener) into the "saltwater" vial and your softened water in the fresh water vial and get results for each. A bargain! And, b) they provide a post-paid envelope to send your water samples in. It takes about a week to get results.

[FishWife]

That’s encouraging, Tom! Great info. I am thinking I might go into this gradually. Maybe get a small tank up and running with a fish or two, some inverts, and some soft corals and then see how they do with the water. I have an old bow front 40 that could be drilled... fitting a sump under it would be a bear so I might put it on a different type of stand... or, perhaps go even smaller... to an Aquapod 24... and see how it goes.

[Origami]

My water comes up with a lot of dissolved CO2 so I was burning through resin so fast that I stopped using it. I then ran an ICP test and found a few metals that were rather low in concentration, but that I still wanted to go after. So, today, I don't worry about the negatively charged ions, I go after the positively charged metals.

 

I cleared a walking path a couple of days ago with my tractor, going back to a small year-round spring that I have back in the woods. (We have several springs around, but they're all small. Most are year-round, but at least one is seasonal.)  I'm toying with the idea of using my small backhoe to dig out an area downstream to form a small, natural pond there.

[FishWife]

My water comes up with a lot of dissolved CO2 so I was burning through resin so fast that I stopped using it. I then ran an ICP test and found a few metals that were rather low in concentration, but that I still wanted to go after. So, today, I don't worry about the negatively charged ions, I go after the positively charged metals.

 

I cleared a walking path a couple of days ago with my tractor, going back to a small year-round spring that I have back in the woods. (We have several springs around, but they're all small. Most are year-round, but at least one is seasonal.)  I'm toying with the idea of using my small backhoe to dig out an area downstream to form a small, natural pond there.

 

Sounds like a fun project.

 

So, I want to summarize here:

 

1. I CAN purify my water using RO/DI, but it MIGHT burn resins pretty fast because of dissolved CO2. I think that this is true of us: "it's likely because CO2 is being added from the air inside your house (where CO2 concentration is typically higher)." I believe that our water softener DOES add CO2. Therefore:  "It sounds like dissolved CO2 should be less of a concern in your case. If that's true, then you should be able to use a standard RO/DI system to clean up your water."

 

QUESTION: can I find out if there's dissolved CO2 by testing pH of water right out of my spring box, before it gets to the softener, overnight and see of the pH drops identically?

 

QUESTION: how many RO/DI chambers should I be looking at "just in case"? 

 

QUESTION: can anyone tutor me on the various kinds of resins? What was written above is Greek to me! Example: ""separating my mixed bed resin and replacing it with two stages of cation resin to go after the positive charged metals (which were still very low, but still something I wanted go after." HUH?

 

2. I should get an ICP test regardless; I can do the "before the water softener" and "after the water softener" vials. 

 

3. When I get the results, I should come back here and ask Tom to interpret them. 

[Origami]

Sorry, Marcia. I was in Las Vegas last week.

 

Most water softeners don't add CO2. If it's the typical setup, it replaces calcium and magnesium ions with sodium ions. However, it's possible that you're using a soda lime softener, which basically adds calcium hydroxide (yes, kalk powder) to the water to precipitate out calcium and magnesium, and, in the process, makes the water pretty alkaline. If this is the kind of softener that you have, CO2 is added on the back end to shift the pH back closer to neutral. The result is water with very little calcium or magnesium hardness, but with a regular balance of dissolved carbonate, bicarbonate and CO2. 

 

QUESTION: can I find out if there's dissolved CO2 by testing pH of water right out of my spring box, before it gets to the softener, overnight and see of the pH drops identically?

 

There's an easy test you can do that will give you an idea of if CO2 is a problem. Take a sample right out of your spring box and check the pH. High CO2 may give you a pH reading of between 5 and 7 (acidic) or lower. Now, take another sample and aerate it for 20 minutes with an airstone and air pump. Take the pH again. If the pH shifted upwards significantly, there's a good chance that the act of aerating the water "blew off" excess CO2, bringing it into closer alignment with levels for the atomspheric air. If the pH doesn't shift by much, then it's likely that you've not got a lot of excess dissolved CO2 in the water.

 

QUESTION: can anyone tutor me on the various kinds of resins? What was written above is Greek to me! Example: ""separating my mixed bed resin and replacing it with two stages of cation resin to go after the positive charged metals (which were still very low, but still something I wanted go after." HUH?

 

Ok. The "huh" made me smile. Pretty direct question. So, most of the time when we buy DI resin from places like AWI and BRS, it's a color changing mixed-bed resin. The color-changing part is self explanatory. But what of the "mixed-bed" part? All that says is that the resin is a mixture of different resins. In this case, an anion resin and a cation resin. If you took a high school chemistry class, you were probably exposed to a unit on electrochemistry. You may have even plated out some metallic copper from a blue solution of copper sulfate.... Anyway, in that unit, there's a positively charged terminal called the anode and a negatively charged terminal called a cathode. Now, these DI resins are actually tiny beads that are constructed so they have an affinity for ions - charged atoms. [simple ions are elements that have extra or missing electrons (e.g. Na+ (sodium), Cl- (chloride)), or more complex ones with multiple elements bound together (e.g. HCO3- (bicarbonate) or PO4-- (phosphate)).] And, inside these beads, there are binding sites that weakly bind ions of a particular charge. It's going to have different affinities for different ions of the same basic charge (positive or negative). Let's take an anion resin, which attracts an positively charged ion or ions (anode - anion, see?). It has an insoluble structure that's negatively charged, but it has a looser electrostatic hold on negatively charged ions that make it overall neutral. For example, might start out with weakly bound sodium (Na+) ions but should a positively charged ion swing by that it has a greater attraction for, say copper (Cu++) or Calcium (Ca++), it'll drop two of those sodium ions and trade it out for the copper ion and still remain electrically neutral. Do you see what's happening? It's trading out sodium for calcium (or copper). Basically, the same thing happens with cation resins but with oppositely charged ions. Cation resins attract negatively charged ions.

 

But DI resin only has a limited number of binding sites. That is, the beads have a fixed capacity after which they start to run out of their benign ion (e.g. sodium) and start trading out the bad stuff for other bad stuff that it has a greater affinity for. For example, let's say that a cation resin has relative affinity for ions arranged sort of like this: Cl- < PO4-- < SO4--. This is hypothetical, but let's say that the resin is exposed to water with both phosphate and sulfate. It starts out by removing both phosphate and sulfate from the water and replacing it with choride. Then, as the resin exhausts, all the chloride has been released and the resin is filled with phosphate and sulfate. Now, if that resin has a greater affinity for sulfate than for phosphate, it'll start to release phosphate back into your output water every time it sees a sulfate ion because it has a greater affinity for sulfate than phosphate in this example.

 

Anyway, mixed bed resins are a mix of anion and cation resins. You can buy anion and cation resins separately or, with some work, can separate a mixed bed into its two resin types.

 

A conventional water softener typically has a big cylinder of anion resin in it that attracts/removes calcium and magnesium from the source water and exchanges it for sodium (or, in some cases, potassium). Then, every few days, it goes offline and a very highly concentrated salt solution is forced through the resin bed to recharge it,. This concentrated solution has the effect of bumping off the more tightly bound magnesium and calcium ion and replacing it with sodum.

 

Bottom line: Since I was going after positively charged dissolved metals (e.g. Copper which might have been added in small amounts from my plumbing), I really only needed an anion resin. Dissolved CO2 has the effect of rapidly exhausting cation resin. My water tests told me that I didn't have negative ions of major concern. So, my solution was to ignore them and to remove cation resin from my stack and use only anion resin. 

 

I hope that helps and doesn't make it even murkier.