ammonium readings in filtered RO/DI water, advice?

[atomictoast]

Hello everyone,
I've been having issues with ammonium readings in fresh made ro/di water lately. I'm using this ro setup from BRS and swapped all the canisters last week, however the problem still persisted. So I upgraded the carbon block to this and took another reading again no change. Here is a picture of my ro water compared to unfiltered tap water, both with salinity at 1.026 and have sat out at room temp overnight. Made a post to reddit and it was suggested I setup additional two canisters one with cation resin followed by a one of anion resin before going to the (still fresh) mixed resin and into my reservoir. So that's what I did. And my ammonium reading has not changed.

Currently TDS going in is around 20, while TDS leaving the mixed resin is at 0. I have used 3 different test kits just to double check if ones not faulty. 2 are red sea NH3/NH4, and both result in the same or similar readings, light green with ro/di water and yellow with unfiltered tap water. I also tested with a salifert NH3 test kit, which constantly reads at or approximately 0 both with tap water and ro water in addition to my tanks water.

 

[KrisReef]

Any reason to believe your carbon filter didn't remove it? Is the test kit bad?

 

[atomictoast]

Any reason to believe your carbon filter didn't remove it? Is the test kit bad?

I have no reason to suspect a bad carbon filter, I swapped the old one out after about 3 months of use to the current one and that has made no difference.

I also don't believe my test kits are bad for either for reasons I touched on in my original post. I'm still able to get a different reading for unfiltered tap water and ro water when factors like salinity and temp are the same. And more importantly I bought a second test kit to verify the results of the first one and they are consistent with one another. Both kits are red sea brand.

 

[Randy Holmes-Farley]

Carbon isn't expected to remove ammonia. The DI mostly does that, along with some help from the ro membrane.

But ammonia is easily displaced from the DI when it begins to deplete. Ammonia in the final effluent can be higher than the incoming water when that first happens.

I'm confused about this last sentence:

" I also tested with a salifert NH3 test kit, which constantly reads at or approximately 0 both with tap water and ro water in addition to my tanks water."

Doesn't that indicate a possible error with the Red Sea kits?

Do they read zero on tank water?

 

[atomictoast]

Carbon isn't expected to remove ammonia. The DI mostly does that, along with some help from the ro membrane.

But ammonia is easily displaced from the DI when it begins to deplete. Ammonia in the final effluent can be higher than the incoming water when that first happens.

I'm confused about this last sentence:

" I also tested with a salifert NH3 test kit, which constantly reads at or approximately 0 both with tap water and ro water in addition to my tanks water."

Doesn't that indicate a possible error with the Red Sea kits?

Do they read zero on tank water?

For the resin I have a hard time beliveing that it's depleted already. There was no colour change with the initial resin but I changed it anyways due to detecting ammonium. The new mixed bed made no differance after running for a couple hours. So I added both a cation and anion canister, ran those for a couple hours and even with those I've detected no differance.

Unless both red sea kits had identical defects I don't know if they where defective. The salifert test kit is only for nh3, not nh3/nh4 like the red sea ones. My problem appears to be with nh4 so it wouldn't be able to detect it unless the test kits are more capable than advertised. The nh3 test kit shows 0 on tank water, and while I won't solely rely on I have a little ammoniaalert submerged in my tank and that too reads on the lowest setting for nh3. Tank ph hovers around 8 too, which supposedly favours the formation of ammonium over ammonia.

 

[atomictoast]

For the resin I have a hard time beliveing that it's depleted already. There was no colour change with the initial resin but I changed it anyways due to detecting ammonium. The new mixed bed made no differance after running for a couple hours. So I added both a cation and anion canister, ran those for a couple hours and even with those I've detected no differance.

Unless both red sea kits had identical defects I don't know if they where defective. The salifert test kit is only for nh3, not nh3/nh4 like the red sea ones. My problem appears to be with nh4 so it wouldn't be able to detect it unless the test kits are more capable than advertised. The nh3 test kit shows 0 on tank water, and while I won't solely rely on I have a little ammoniaalert submerged in my tank and that too reads on the lowest setting for nh3. Tank ph hovers around 8 too, which supposedly favours the formation of ammonium over ammonia.

oh unless you ment if the red sea test kits read zero on the tank. No they do not they read rather high lime 1.2 ppm high.

 

[Randy Holmes-Farley]

It sounds most likely a test kit or user error to me. Not ammonia in the tank or the new fresh water.

The Salifert kit detects total ammonia, and it is not the case that you can have ammonia without ammonium or the other way around. They rapidly interconvert.

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www.salifert.com

"The Salifert Ammonia test is very straightforward and measures the sum of toxic ammonia and ammonium in just a few minutes.
The kit can perform approx. 50 measurements and can detect 0.5 ppm of total ammonia easily."