sodium hypochlorite and RO/DI?

[TDEcoral]

I've been having trouble getting my acros to thrive and I started wondering if my water district was using chloramines for treatment. I got an email from them this morning that they use "on site sodium hypochlorite" at all of their wells. From some googling it looks like this is the active ingredient in bleach.

My question is, will this damage my ro/di filters? Will it make it through a 5 stage system? Should I be using Prime in my ro/di container after making some water? Any advice will be much appreciated.

 

[rmurken]

Good on you for contacting your water utility.

A five-stage RODI system should easily remove all the chlorine (i.e., sodium hypochlorite). Specifically, the carbon stage that comes before the RO filter is meant to remove chlorine (among other things), since otherwise, as you suggest, the chlorine could damage the RO membrane. So you should be fine as long as your carbon stage is good.

Sodium hypochlorite and bleach are indeed one and the same. But see above.

 

[MnFish1]

Good on you for contacting your water utility.

A five-stage RODI system should easily remove all the chlorine (i.e., sodium hypochlorite). Specifically, the carbon stage that comes before the RO filter is meant to remove chlorine (among other things), since otherwise, as you suggest, the chlorine could damage the RO membrane. So you should be fine as long as your carbon stage is good.

Sodium hypochlorite and bleach are indeed one and the same. But see above.

Except it depends on how otften you replace your filters - and how much they are using. Have you ever measured with a low-dose chlorine test? (i.e. highly sensitive) - My guess is that your filters are taking care of it as @rmurken says

 

[rmurken]

Will chlorine show up on a TDS meter? I know some things don’t—or don’t show up well—but am thinking chlorine would? Therefore if 0 TDS, good to go....if my theory is correct.

 

[x2uranium]

Per cdc...
Chlorine levels up to 4 milligrams per liter (mg/L or 4 parts per million (ppm) are considered safe in drinking water. At this levelExternal , no harmful health effects are likely to occur 2.

 

[TDEcoral]

Will chlorine show up on a TDS meter? I know some things don’t—or don’t show up well—but am thinking chlorine would? Therefore if 0 TDS, good to go....if my theory is correct.

That's what I was wondering as well because my TDS meter is reading 0. My next step is to test my ro/di output for chlorine.

 

[Malcontent]

TDS won't detect it. Get a test kit that can read down to 0.02 mg/L total chlorine.

 

[rmurken]

This piqued my curiosity. My impression from casting around Google is that a typical TDS (conductivity) meter can still show 0 TDS even with some level of chlorine persisting in the RODI output water. Same goes for phosphate and other substances that are non-ionic or only weakly so (and in fact I can detect some phosphate in my RODI water with a test kit, even though it’s 0 TDS).

I’m no SPS guy so it may be that you would want to try to rule out chlorine as a cause of your acros’ failure to thrive.

 

[Malcontent]

If it was possible to detect chlorine using conductivity, water treatment plants would use it.

This is the closest you can get to measuring by conductivity and it seems like a lot of trouble if a simple conductivity meter would suffice.

 

[MnFish1]

TDS meters do not detect CL- - on the other hand - most of the things that we have linked to our other hardware (carbon blocks, possibly DI) remove it - unless they are ehausted. thus - if you are using only tds you may be underestimating cl - but - probably not

 

[TDEcoral]

Thanks for the info everyone! I'm going to test the output on my ro/di and I'll report back.

 

[PedroYoung]

The chlorine itself as a contaminant is probably not as worrisome as the effects of the Cl2 on the RO membrane. If the membrane is damaged then all sorts of other contaminants would be let through (picked up as TDS on the outlet of the membrane). Cl2 is pretty unstable and is dosed in municiple water systems at pretty low levels (usually they are trying for 1 ppm as it leaves the water tower) otherwise their piping systems are in danger. If you're changing your carbon canisters frequently it shouldn't be a concern.

 

[ScottR]

I've been having trouble getting my acros to thrive and I started wondering if my water district was using chloramines for treatment. I got an email from them this morning that they use "on site sodium hypochlorite" at all of their wells. From some googling it looks like this is the active ingredient in bleach.

My question is, will this damage my ro/di filters? Will it make it through a 5 stage system? Should I be using Prime in my ro/di container after making some water? Any advice will be much appreciated.

I’m sure this isn’t the reason your acros don’t thrive. It was a good hunch on your part but there are so many other factors and keeping an open mind and exploring all other probabilities may lead you to find an answer.

 

[TDEcoral]

I’m sure this isn’t the reason your acros don’t thrive. It was a good hunch on your part but there are so many other factors and keeping an open mind and exploring all other probabilities may lead you to find an answer.

You're response is kind of patronizing. I'm not new to reefkeeping or acros. The only reason I'm looking into this is because I've already explored just about every other option.

 

[Kyl]

Another thing to keep in mind, if a city is doing main work, or even routinely a year, they will flush the main with high levels of chlorine before returning it to service. That can be enough to over-whelm your carbon blocks and destroy your membranes if not watched out for.

 

[ScottR]

You're response is kind of patronizing. I'm not new to reefkeeping or acros. The only reason I'm looking into this is because I've already explored just about every other option.

My apologies for coming off as patronizing as that wasn’t my intent. Have you done an ICP test to rule out all other possibilities?

 

[Randy Holmes-Farley Verified Community Expert]

The carbon block of an ro/di is designed to remove chlorine, mostly to save the membrane as folks have noted. It is unlikely that there is any problem, but a cheap chlorine kit can be used to test for it and chloramine in the final effluent.