Nitrate spike

[stevieduk]

Just tested my water and nitrates have gone halfway up the scale, but nitrites are perfect. We have traced it back to my R/O unit , and the filters starting to go off and letting nitrates in the tapwater through, so the last two water changes i have done , i have just been adding nitrates to the system.
I have been told that , apart from the TDI meter, you cannot test plain R/O water for nitrates and things because there are not enough ions in it to get a true reading, and you only get a true reading when you add the salt back to it.
So how do you test it to see if your RO unit is ok, without wasting a load of salt.
Any ideas anyone

 

[saltyfilmfolks]

Did you see a change in the tds?
Do you have a handheld tds meter ?

 

[stevieduk]

yes have a handheld tds meter and there was only a tiniest change in the reading , like 0.1 or 2. also took a sample to local fish store and there test was the same, but when salt is added there is a high nitrate reading in my water. so i have had to throw away 80 gallons of freshly made salt water , and buy that amount of water from the fish store, plus the salt.
i have ordered new cartridges for my R/O unit,(more cost ), but there must be a way of testing the water before adding the salt to stop more waste

 

[saltyfilmfolks]

I would use a fresh water nitrate test.
Or have the lfs test it if they do fresh water.

 

[Lasse]

I have been told that , apart from the TDI meter, you cannot test plain R/O water for nitrates and things because there are not enough ions in it to get a true reading, and you only get a true reading when you add the salt back to it.

Have you tested your tap water?

Normally - the chloride ion lower you test reading. The scale you read your NO3 level from should be adjusted to show a higher value compared with what the test show. if you use a sample without chloride ions - the read from your scale should be to high - not to low (if my brain function well for the moment)

I have a feeling of that tests on fresh mixed saltwater always show wrong. I never test fresh water - have it to stand for 24 hours before testing


Sincerely Lasse

 

[stevieduk]

Have you tested your tap water?

Normally - the chloride ion lower you test reading. The scale you read your NO3 level from should be adjusted to show a higher value compared with what the test show. if you use a sample without chloride ions - the read from your scale should be to high - not to low (if my brain function well for the moment)

I have a feeling of that tests on fresh mixed saltwater always show wrong. I never test fresh water - have it to stand for 24 hours before testing


Sincerely Lasse

but they say you can not test r/O water as there are not enough ions in the water to get a nitrate reading and find out if your R/O filters are working properly

 

[saltyfilmfolks]

but they say you can not test r/O water as there are not enough ions in the water to get a nitrate reading and find out if your R/O filters are working properly

If there are enough nitrate ions in the water to cause you problembs then if you test the to no3 for you'll read nitrates no?

 

[Lasse]

but they say you can not test r/O water as there are not enough ions in the water to get a nitrate reading and find out if your R/O filters are working properly

Do they mean that other ions (beside the nitrate ions) has an importance in the measurements? The lack of chloride ions in RO will make the readings higher IMO. I do not really know if it’s possible to use the saltwater tests in RO. Probably you get a wrong reading – but to high IMO not zero. But if someone says – it´s not possible – I want to know why. What they say to you indicate that they think the ion strength of the sample will affect the test – in general – I do not believe that explanation (beside the chloride ions)

What levels do you read – with your present test – in the tap water, in the RO water and in.the aquaria?

Sincerely Lasse