Neptune Trident NP phosphate reading drifting lower after running for days or weeks – Root Cause

[RelaxingWithTheReef]

Initially my Trident NP tester was tracking well, and able to correctly report a 0.10 ppm spike addition to the water sample. But after running for a week or so, my 0.05 ppm reading started to drift down. After a couple weeks I ran another spike test, and the 0.10 ppm addition resulted only in a 0.02 ppm reading increase. Nitrate tests have always been good, and I am running the latest software.

The problem was finally tracked down incredibly to the black tank sampling tubing. There was evidence of significant bacteria growth inside the tubing likely resulting in some restriction. I suppose it’s also possible the bacteria can consume some of the phosphate as the sample water works its way through the tubing. Randy - If you are reading this, is this possible? But, I have to be clear that I simply do not know the exact reason the tubing altered the test result. I can tell you the value drifted lower due to a change in the tester’s phosphate chemical reaction, and not a drift in the electronics or software. Ultimately, replacing the sample tubing with the exact same tubing from another Trident tester restored the sensitivity.

Unfortunately this is not a long term solution as I can’t change the tubing every week or so. I am not even sure how to clean such small diameter tubing.

I’m wondering if other people are experiencing the same issue, or have a solution.

 

[areefer01]

Initially my Trident NP tester was tracking well, and able to correctly report a 0.10 ppm spike addition to the water sample. But after running for a week or so, my 0.05 ppm reading started to drift down. After a couple weeks I ran another spike test, and the 0.10 ppm addition resulted only in a 0.02 ppm reading increase. Nitrate tests have always been good, and I am running the latest software.

The problem was finally tracked down incredibly to the black tank sampling tubing. There was evidence of significant bacteria growth inside the tubing likely resulting in some restriction. I suppose it’s also possible the bacteria can consume some of the phosphate as the sample water works its way through the tubing. Randy - If you are reading this, is this possible? But, I have to be clear that I simply do not know the exact reason the tubing altered the test result. I can tell you the value drifted lower due to a change in the tester’s phosphate chemical reaction, and not a drift in the electronics or software. Ultimately, replacing the sample tubing with the exact same tubing from another Trident tester restored the sensitivity.

Unfortunately this is not a long term solution as I can’t change the tubing every week or so. I am not even sure how to clean such small diameter tubing.

I’m wondering if other people are experiencing the same issue, or have a solution.

The black colored line is the water sample line as you are aware. If you swapped out the line and had a different result then my guess would lean more towards a blocked line. This could reduce the amount of water the NP thought it had in the test chamber and therefore alter results.

I don't believe I've read anything with the original Trident running into the tubing fouling tests. Blockage yes, altering test results, no. Doesn't mean it isn't possible I guess. In any case did you reach out to Neptune support? What did they say.

 

[RelaxingWithTheReef]

The black colored line is the water sample line as you are aware. If you swapped out the line and had a different result then my guess would lean more towards a blocked line. This could reduce the amount of water the NP thought it had in the test chamber and therefore alter results.

I don't believe I've read anything with the original Trident running into the tubing fouling tests. Blockage yes, altering test results, no. Doesn't mean it isn't possible I guess. In any case did you reach out to Neptune support? What did they say.

There was no change in the amount of water in the test chamber between the two sample lines. The tubing may have had a slight restriction, but it was not clogged. That's one of the things that made the issue so difficult to resolve.

Neptune has been extremely quiet regarding issues with this product, frustrating a lot of people. I have not reached out to them yet.

 

[rtparty]

Are you on the latest firmware?

 

[RelaxingWithTheReef]

Are you on the latest firmware?

Yes, latest software and firmware update.