Accuracy of Neptune Systems Trident NP

[SeaTee_Aquatics]

Has anyone else here gotten the new Trident NP and what kind of accuracy are you seeing from the device? Currently I have a few of these running and the readings are totally inconsistent, all over the place, and not at all near the actual readings I’m getting on other test kits. I’ve tried using the unit without calibrating and after calibrating and have issues both ways. Let me know if anyone else had this issue and how they may or may not have fixed it.

 

[Gumbies R Us]

Bumping your post!

 

[rtparty]

There are a dozen plus posts on this topic that a search will bring up. Major issues with PO4 readings.

However, there was a major update yesterday that looks like it may have fixed things.

 

[Cranie]

There are a dozen plus posts on this topic that a search will bring up. Major issues with PO4 readings.

However, there was a major update yesterday that looks like it may have fixed things.

I did the update yesterday morning. PO reading shot up but then on a retest it went back to what it read preupdate. I have yet to do a cal but I'm holding off as "working" is better than not.

 

[MrLargo]

My NP PO4 says .09 and Hanna ULR says .21. Which do I trust??

I am dosing Lantham to get PO4 down from high levels, and now that I am getting lower, I really want to know which to trust!

 

[Cranie]

Yesterday my Trident says .41 PO4 Hanna says .11 I dosed Phos RX. Today it read .42 I ran a calibration for the first time. It reads.... .41 As far as NO3 it's accurate but PO4... it's just about guessing.

 

[MrLargo]

Yesterday my Trident says .41 PO4 Hanna says .11 I dosed Phos RX. Today it read .42 I ran a calibration for the first time. It reads.... .41 As far as NO3 it's accurate but PO4... it's just about guessing.

I did the calibration, too. According to Neptune that is more for adjusting the head pressure for the height of the sample line, instead of changing the readings...‍

 

[Gho5t]

For what it’s worth, I did side by side Hanna tests when the NP was testing over several days and I had nearly identical results.

 

[MrLargo]

For what it’s worth, I did side by side Hanna tests when the NP was testing over several days and I had nearly identical results.

 

[Cranie]

For what it’s worth, I did side by side Hanna tests when the NP was testing over several days and I had nearly identical results.

I think the PO4 test is reliant on a lot more than "take a sample, add reagent, stir, read" like tube length and that filter on the sample line (WHY I don't know). I do PO4 tests at work every day and it's dead simple. I don't know what the big issue is on the NP.

 

[Gho5t]

Ha definitely! I forgot to mention that my LFS did the same Hanna comparisons and their results matched as well so I’m feeling pretty good about it at this point.

 

[Jimbo327]

Ha definitely! I forgot to mention that my LFS did the same Hanna comparisons and their results matched as well so I’m feeling pretty good about it at this point.

Please report back in a month. Some users have said their unit was working great, then the phosphates started to drift and not match the Hanna.

 

[RusticsReef]

For what it’s worth, I did side by side Hanna tests when the NP was testing over several days and I had nearly identical results.

sounds like you're the only one!

 

[areefer01]

sounds like you're the only one!

No, their not. It does, however, go to show how two hobbyist can use the same piece of equipment and have different experiences. Sometimes it is obvious what those are. Others it isn't.

 

[dakoop]

Mine is accurate. At least that's what I'm telling myself.

 

[Cranie]

My NItrates have been accurate. PO4 has consistantly been about .36 high no matter what I do.

 

[RelaxingWithTheReef]

Out of the box after the software update and factory reset, my nitrates are spot on, but the phosphate reading is extremely inaccurate. After spending way too much time troubleshooting, I have identified two significant problems and sources of error.

1. The thin black water sample tubing grows an internal biofilm that significantly reduces the phosphate level of the sample water before it reaches the tester. In some cases the tubing can reduce the phosphate level of the sample water to essentially zero before it reached the tester.

2. There is a fixed offset or shift of the tester’s phosphate reading that seems to be different with every batch of reagents. For my first batch I had to subtract 0.425 ppm from the reading to get the correct result. With the second batch, I have to subtract 0.035 ppm.

The good news is as long as the tester has a good water sample, and you subtract the offset, you can seemingly get an accurate phosphate reading. The tester consistently and accurately reports a 0.100 ppm phosphate spike to the sample, and this is very encouraging.

The ball is in Neptune’s court. They need to come up with a fix to get an uncompromised water sample into the tester, and they should allow users to calibrate the device like the original Trident.

 

[areefer01]

1. The thin black water sample tubing grows an internal biofilm that significantly reduces the phosphate level of the sample water before it reaches the tester. In some cases the tubing can reduce the phosphate level of the sample water to essentially zero before it reached the tester.

The line as you are aware is a sample line - drawing water in from the source location to the test chamber. Are you suggesting that it is either contaminating the sample or that it isn't allowing proper water sample size and thus throwing off the tests.

 

[RelaxingWithTheReef]

The line as you are aware is a sample line - drawing water in from the source location to the test chamber. Are you suggesting that it is either contaminating the sample or that it isn't allowing proper water sample size and thus throwing off the tests.

I have no evidence the tubing contaminates the sample. At one point I replaced the tubing with BPT tubing, and had the same result. The phosphate reading decreased day by day.

There is no evidence of a restriction in the tubing. The testing cuvette always fills to the proper level.

For confirmation of this idea, I drew 1 ml tank water from the tube every 5 minutes to collect a 10ml sample. The tank water directly measured 0.060 ppm, and the sample from the tubing measured 0.010 ppm. Repeating the test with a new length of tubing did not reduce the phosphate level.

I repeated this experiment a couple times, and the only plausible explanation I can come up with is a biofilm develops on the inside surface of the tube that is capable of quickly absorbing the available phosphate.

To put things in perspective, the tubing has an inside diameter of approximately 0.020”, and the 5 ft length holds around 1.25 ml of water. But the surface area works out to be 3.8 square inches! It’s a surprisingly large amount of surface area that appears to host enough bacterium to very quickly remove the available phosphate.

 

[Jimbo327]

Maybe that's why Maven has an air pump to clear the line.