need help intrepreting some test results

[JonsReef]

so i just purchased a test kit for mg/kh/ca, three parameters which i have never tested before. i have a BC14 and do weekly 3 gallon water changes and have relied on this method to replenish trace minerals. i test the basic params every few days. here are my current parameters. can anyone offer any suggestions/guidance/feedback/etc...

Temp: 78
pH: 8.4
Salinity: 1.026
ammonia: 0
nitrite: 0
nitrate: 0
phosphate: 1-2 (coming down)

mg: 1500ppm
KH: 3.3 meq/l (9.2 dKH)
ca: 635ppm

the Mg and CA levels seem a bit high to me. i am using tropic marin pro reef salt.

 

[Turbosnail]

Did you only test once if so you might want to test again just to make sure. what are you using for a test kit api, elos.....

 

[JonsReef]

the basic test kit (ph/amm/rites/rates/phos) is an API, the new test kit for Mg/Ca/KH is RedSea. i will test again, but im pretty confident in the results since the tests are titration-based and i'm an analytical chemist by education.

heres a link:

http://www.saltysupply.com/Red-Sea-Reef-Foundation-Pro-Ca-Alk-Mg-Multi-Test-K-p/rs21510.htm

 

[stingythingy45]

What salt mix,are you dosing anything?
I wouldn't be concerned.A MG of 1500 ppm is nothing to worry about.
And I would think the Ca. test might be skewed by something.I've never had any luck with Red Sea test kits(old type).
So not sure how the new ones are.I would purchase a calcium API kit and test that Red Sea against it.

 

[Andy V]

the basic test kit (ph/amm/rites/rates/phos) is an API, the new test kit for Mg/Ca/KH is RedSea. i will test again, but im pretty confident in the results since the tests are titration-based and i'm an analytical chemist by education.

heres a link:

http://www.saltysupply.com/Red-Sea-Reef-Foundation-Pro-Ca-Alk-Mg-Multi-Test-K-p/rs21510.htm

I don't care what your education is, it's awfully hard to interpret the end point color on those new Red Sea tests...I have them too. And unless you mysteriously got a bad batch of a very reliable salt, you either conducted the test incorrectly or interpreted the end point incorrectly. I used that salt for years and the calcium is not even close to what you are reading. I am not trying to be a jerk, just stating the facts.

 

[JonsReef]

i am using the tropic marin reef pro salt. i am not dosing anything.

they told me at skiptons yesterday that there had been some bad batches of the tropic marin reef pro salt in the last few years, which is why they no longer carry it. i'm not sure how true that is. i think i will test my RODI water and then some "fresh" salt mix to compare that with my water column test results.

the theory behind titration-based tests is that the results should actually been less prone to colorimetric interpretation than the old tests that made you compare a color to a range of colors on a color wheel or chart. if you perform titration correctly, there really shouldn't be much ambiguity or room for interpretation. either the color should change and stay changed if you have reached the titration point, or it will briefly change to the end color and then revert to the starting color as you approach the titration point. if you do this carefully, the tests should be more accurate than the older style tests. however, this is all great in theory but i dont have much actual experience with these tests yet.

im really not trying to get into a pissing match about the validity of the testing process, etc. i just wanted some input on what people thought of the actual results.

 

[inverted]

I wouldn't trust the test results either, they are way to high for TMP. Even if the batch was bad, it's not that bad...

TPM should mix to about 450 ppm ca, 8.5dkH and 1380ppm mg. @ s.g. of 1.0264.
(from here:http://www.reefcentral.com/forums/showthread.php?t=1714505).

I've used it and don't anymore because of the consistent low numbers. It's my understanding that it's actually made to be low and is intended for people who dose a lot via calcium reactors.

However, the Red Sea kits are absolute junk IME. People get very inconsistent results with them, all over the board. I think that is likely the source of the problem. The numbers aren't bad, they just aren't right...

 

[JohnK]

How is salinity being tested? The numbers look a lot like the salinity is higher than 1.026, and if so that would explain everything.

 

[inverted]

How is salinity being tested? The numbers look a lot like the salinity is higher than 1.026, and if so that would explain everything.

That would make sense, but then they should all be off roughly proportionally. They aren't. Also, the ca is 40% high, that would mean the s.g. Would need to be about 1.036. That's roughly at the level salt mixes will saturate.

 

[Andy V]

the theory behind titration-based tests is that the results should actually been less prone to colorimetric interpretation than the old tests that made you compare a color to a range of colors on a color wheel or chart. if you perform titration correctly, there really shouldn't be much ambiguity or room for interpretation. either the color should change and stay changed if you have reached the titration point, or it will briefly change to the end color and then revert to the starting color as you approach the titration point. if you do this carefully, the tests should be more accurate than the older style tests. however, this is all great in theory but i dont have much actual experience with these tests yet.

The issue with these tests is that the color change is not obvious. They actually have videos on youtube of how to conduct the tests properly. You will see in those videos that the color starts to change and looks pretty purple to me, but the tester says it's pink. It sort of changes shades over several drops which is exactly the problem with them.

 

[JonsReef]

the salinity is being tested with a refractometer that i recalibrate with each new batch of RODI water.

im mixing up a new batch of the TMP saltwater now and will test that. the test results i posted above were from the water column, but i have been using this salt for a while with seemingly good results.

i was doing some reading and it seemed that TMP did have some issues with clumping in their salt mixes. i did notice in the box i have that there were some clumps, but nothing that couldnt be broken up easily by shaking the box.

is there a shelf life on salt mix?

 

[JohnK]

OK, then you shouldn't be far off. (FWIW it's reccomended to calibrate refractometers with a standard saltwater solution because the curve can be off over a range of salinities. I'm off to find a link/ref on that.....)

Edit, here's that link;
http://reefkeeping.com/issues/2006-12/rhf/index.php

 

[JonsReef]

thanks for the link. ill look into making a standard solution for the refractometer.

so i tested a fresh made batch of TMP saltwater and this is what i found. ph and ca reading seem a bit off i'd say.

salinity: 1.026
ph: 8.8+ (is this normal?!?!)
ammon: 0
rites: 0
rates: 0
phos: 0
ca: 650 (high??)
mg: 1520
KH: 2.5 meq/l (7.0 dkh)

 

[Andy V]

I have a difficult time believing your calcium is that high with alkalinity that low. It's also hard to believe that your alkalinity is that low with pH that high.

It just doesn't make any sense at all. That is unless your tank looks like it's snowing...meaning stuff is precipitating out of solution.