should I be worried?

[Leon821019218]

So I've done an ATI ICP test this week to see if my parameters were improving over the last time I did one (February of this year)
Overall I had a better 'score' then last time (83% then against 96% now). But a few things bother me.

I've had some issues with my salinity because of a faulty refractometer, see my build threat for the whole story (https://www.reef2reef.com/threads/leons-95-gallon-reef.906530/#post-10134982)
So I bought a Milwaukee digital salinity checker and as far as I knew my salinity was now on the right track at 35/34PPT
In the test results it says my salinity is 33.05 PSU, as far as I know are PSU and PPT basically the same so there is a 2 point difference between my calculations and ATI's.
Which seem much? My Milwaukee checker is brand new and I calibrate before every test with RO water so who to believe.. my checker of the ICP test.

For measuring my KH i use a Hanna checker and it gives me a KH between7.5/7.8 for the last week or so (had to up my dosing). According to the test I have a KH of 9.34. Also quite a big difference right?

Another one that's a bit strange is my P04, it says I have 0.39 µg/l and the ideal value according to them is 0.04... When I test my P04 (salifert) most of the time it's hardly readable so 0.39 is pretty high right? Big difference. So any tips for a more correct way to measure P04?

And finally I have to high Zinc and Tin Zinc at 26.92 µg/l and Tin at 8.91 µg/l. Where can this come from? I use tropic marine pro salt (made in Germany) and my RO water test came clean. Nothing elevated with metals of what so ever.

Any pointers, tips or tricks are welcome

 

[blaxsun]

From everything I've read, salinity is always off on the ICP reports. And because the salinity is off, all the other measurements are (slightly) off as well. Personally, I'm beginning to gravitate to the belief that these lab tests are more hype than help. With the (minor) exception of zinc and tin - everything looks fine (and I'm not sure I'd even worry about those). From what I can see there's nothing really glaring in this report.

Tropic Marin Pro Reef salt is some of (if not the) best salt you can use - and I use the same. Honestly, I'd go off your own alkalinity, salinity and phosphate tests. I use Nyos and Hanna for my main parameters and they're always fairly close.

 

[Woodyman]

Two questions I have.

Is calibrating with RO the correct way for the Milwaukee meter?

A calibration performed with RO and one performed with a standard at 35ppt do not always line up the same. I don't have a Milwaukee so I'm just asking to ask, you might not be able to calibrate with a 35ppt standard.

When you got the RO/DI sample did you get straight out of the tubing after the last DI, or out of your storage/holding container?

 

[Leon821019218]

From everything I've read, salinity is always off on the ICP reports. And because the salinity is off, all the other measurements are (slightly) off as well. Personally, I'm beginning to gravitate to the belief that these lab tests are more hype than help. With the (minor) exception of zinc and tin - everything looks fine (and I'm not sure I'd even worry about those). From what I can see there's nothing really glaring in this report.

Tropic Marin Pro Reef salt is some of (if not the) best salt you can use - and I use the same. Honestly, I'd go off your own alkalinity, salinity and phosphate tests. I use Nyos and Hanna for my main parameters and they're always fairly close.

You may have a point there. All though it can be helpful (especially when you want to know if there are metals in the water) it also can make you second guess yourself and your measurements... yeah, i'm very happy with TM, it may not be cheap but it's very good.

 

[Leon821019218]

Two questions I have.

Is calibrating with RO the correct way for the Milwaukee meter?

A calibration performed with RO and one performed with a standard at 35ppt do not always line up the same. I don't have a Milwaukee so I'm just asking to ask, you might not be able to calibrate with a 35ppt standard.

When you got the RO/DI sample did you get straight out of the tubing after the last DI, or out of your storage/holding container?

It's says in the user guide that it has to be calibrated with distilled or deionized water. I used RO water directly from the tube

 

[Woodyman]

It's says in the user guide that it has to be calibrated with distilled or deionized water. I used RO water directly from the tube

Tube water vs storage container water may not always be the same.. ultrapure water sitting in containers has a tendency to pick things up. So while I wouldn't to much, on your next ICP test it from the tank instead.

 

[Leon821019218]

Tube water vs storage container water may not always be the same.. ultrapure water sitting in containers has a tendency to pick things up. So while I wouldn't to much, on your next ICP test it from the tank instead.

But should water directly from the RO unit be the most 'pure' sample? So that it gets you the most accurate readings? Or am I misreading?

 

[Woodyman]

But should water directly from the RO unit be the most 'pure' sample? So that it gets you the most accurate readings? Or am I misreading?

Yes from the tubing will be the most pure.

However unless you always top off directly from the unit your not getting a representative sample of how the water changes while sitting in your storage container.