Water. Ammonia. From where?

There are a couple of issue possibly at play here.

First is Chloramines. Whoever told you to let your water sit overnight may have assumed that your city water was treated with Chlorine. If that is the case, then letting tap water sit out overnight under agitation (like an airstone or powerhead pointed to the surface) will indeed offgas the chlorine pretty well.

Chloramine however, does not offgas. Chloramine is a derivative of ammonia in which one to three of the hydrogen atoms is substituted with Chlorine. Not as if that matters but what you need to know is that you must chemically neutralize this with Prime or something else that can break the chlorine-ammonia bond. Your test kit may be inconveniently doing this for you which results in a false positive.

The bottom line is that you can use tap water and Prime in a freshwater tank, and that is actually best, as RODI strips the water to nothing. RODI water must have things added to it in order to create a balanced water for freshwater tanks

RODI is what you want for a reef tank, because the salt mix has everything in it to balance it to the salinity and other chemical levels that you need. It is also good for top off water.

The other thing - on your culligan system. Test that with a TDS meter and you will find that the water in your pressure tank that you drink out of is really high in TDS compared to the desired zero. This is because as the pressure in the tank increases, backpressure is created on the membrane and this mean that dissolved solids can migrate over more easily and your TDS starts to creep up. This is a slow process so what happens is as your tank comes up to pressure, more TDS gets across untl the tank is full and you produce no water. The water then sits there, in the membrane housing, and a bunch of DS creeps across. Then you get yourself a glass of water and there is a rush of high TDS water one the production water side of the membrane that gets flushed into your holding tank. That's why your pressure tank is not what you want to use for top off - at least not regularly.

If you want top-off water, get a couple valves, shut off the connection to the pressure tank, tap off of the production line to a 5g bucket, and make it separate with zero outlet pressure (after you flush out the membrane for 30-60 seconds and test your TDS). You can also add a simple DI canister to polish that RO water up nicely.

My opinion on Culligan drinking water systems is not good. You can get a much higher quality system for 1/10th of what they charge.

 

I had an interesting discussion with BRS yesterday about this. When I ordered the filters for the DSM holiday party door prizes they included a flyer about chloramines so this applies pretty much to every large municipality in Iowa I think.

BRS has been testing a lot of different carbon blocks and has come up with a new recommendation, they have posted a few videos of this recently as well. When you order an RODI unit, they now send a chloramines test kit.

The issue apparently is the that standard carbon block will break down chloramine and this results in free chlorine and free ammonia. Ammonia can get through the RO membrane apparently so this might explain what you are seeing but I'm not 100% sure.

It sounds like if you have chloramines then they recommend actually using 2 of the chloramine carbon blocks, which have a blue trim on them. I run the 6 stage which has the sediment pre-filter and then the 1 micron & 0.5 micron carbon block (white & purple trim) and he said replace the white one with the blue one, and if possible to actually replace it with 2 of the blue ones. Why it is only showing up when you mix the water is odd but a few questions/clarifications:

When you make up a batch of water, have you tested it (with no salt mix) after sitting out with the top off versus sealed?

When you mix up a batch of saltwater - same question - tested after covered vs uncovered?

What salt mix are you using? Apparently (I didn't know this) some salt manufacturers add an ingredient to decholrinate and/or de-chloramine the water. Both of these would result in a false positive. Things like Prime will bond with nitrogen compunds like ammonia and nitrate and nitrite but some test kits will break the bond and give you a false positive. I know that with Prime the nitrate bond is temporary so if you have high nitrates in your tank you can neutralize them but it starts to 'wear off' in a few days.

The other thing we talked about was the membranes. He said that chloramine will "cook your membrane" i.e. break it down faster which allows more junk to get through. This might explain a few things for some people watching this thread. But he also said that chlorine is the hardest on membranes to which I brought up something they were not aware of which honestly worries me a bit:

There are different RO membranes for different uses. One is made for use on chlorinated water, and one is made for use on non-chlorinated water (well water). I believe the difference is that the one for well water contains some kind of antibacterial layer or coating or something like that to prevent the membrane from becoming a home for a bacterial colony, whereas the one for use on chlorinated water does not need this. So my gut tells me that the Dow Filmtec membrane is for chlorinated water as this is the scenario under which an RO unit is most commonly used.

So I think the answer here appears to be that you need to replace the white carbon block with a blue one, but I'm not totally sure on that yet. He said the standard (white) carbon block gets eaten up pretty fast (6-700 gallons) and while the chloramine block gets eaten up as well, it takes a lot longer (3-4 times longer)

He also mentioned something about using a difference sediment filter if you do away with the white block, but I think that depends on how gunky your water is. The way to know this is if your sedminent filter turns brown quickly. Mine does not, it stays pretty white for 100s and 100s of gallons of RODI produced.

So it looks like what I will personally be doing is turning my 6 stage (3 pre filters, membrane, dual DI) into a 7 or 8 stage. I'm going to add in another canister, get 2 of the chloramine blocks, and maybe add another prefilter.

From the sounds of it, we should all be replacing the chloramine block every 1500-2000 gallons or something like that. This is all new to me and sounds like its new to them as well really.

 

good link

http://www.thefilterguys.biz/chloramine_filters.htm

 

Huh I thought they did. Good to know, thanks J

 

I just sent The Filter Guys a message with a bunch of questions, I'll see what they say

 

Cedar Rapids uses chloramines. I run 1 of the chloramine filters as recommended from AWI, but maybe I should look into changing my setup as well.