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-   -   Bogus AWT results? (http://www.reefcentral.com/forums/showthread.php?t=1509295)

gkyle 11/12/2008 06:11 AM

Bogus AWT results?
 
Following an earlier thread, I decided to give the AWT water testing a try. From my perspective, their numbers are bogus. Here's what they said:

Ammonia (NH3-4) ..................Good ............................... 0.007
Nitrite (NO2)...........................Good ............................... 0.008
Nitrate (NO3)..........................Good ................................1.0
Phosphate (PO4) .................. High................................. 1.24
Silica (SiO2-3) ....................... High..................................0.7
Potassium (K) .........................Low................................. 295
Calcium (Ca)............................Low................................. 342
Boron (B) ................................Low..................................0.4
Molybdenum (Mo)....................Good ...............................0.0
Strontium (Sr) .........................Good ...............................9.3
Magnesium (Mg) .....................Good .............................. 1388
Iodine (I¯)................................Good ............................. 0.03
Copper (Cu++) .......................Good .............................. 0.01
Alkalinity (meq/L).....................Good .............................. 3.69

The really bogus number is phosphate, but calcium and silica are also suspect. Here are my numbers - tested with the same water I sent:

Calcium - 470 (Elos new kit), 480 (Tunze/Machery-Nagel), 500 (Salifert)

Phosphate - 0 (Elos), 0.01 (Martini photometer)

Silica - not tested

My rationale:

1. I use only balanced Alk/Ca sources - Kalk and Ca reactor. Alk consistently measures 11-12 on my Elos and API kits, and 13-14 on Salifert. Given that three kits show Ca in the 470 range (what I would expect with my Alk numbers), I can't imagine an actual Ca value of 342.

2. A few months ago I had a bad algae problem and my Elos kit showed .05 phosphate at the time. I then purchased the photometer and it showed 0.09. Since then I've swapped over 600g of water, added more GFO, and started dosing sugar. I currently have no algae issues at all. With a value of 1.24 as they report, I would expect nothing but green throughout my tank. Also, I run a skimmer rated at over 1,500g.

3. I haven't tested silica, but my lack of diatom growth suggests that I don't have an issue. I do run "silica buster" DI resin, and my TDS has been zero for months. I also run almost 3 cups of GFO in two reactors and change it every two weeks. I run a BB tank, and I do a minimum of 50g water change weekly using Kent salt, mixed and aerated in a 210g reservoir. Five days before this test I changed 100g to bring down my Ca and Alk numbers.

Overall, a huge disappointment. The only other water testing source I found was the same price for only one parameter. So, sadly I went the cheap route. :confused:

HighlandReefer 11/12/2008 06:34 AM

Based on your results & many other hobbyists results, I would not trust them. My local club went through a phase where a lot of them sent off their samples. Came back with results, similar to your's. :D

kaskiles 11/12/2008 06:37 AM

Maybe the sample of water had a lot of dissolved organics and live bacteria in it. So your immediate tests were more representative of the actual state of the living water, but by the time the sample got to AWT, it had changed. Suspended bacteria had expired, organics had reacted and changed.

Can you do another, but this time pull two samples at the same time? Send the one to AWT, and tell them to call you when they start testing it. When they call, then start testing the second sample you kept home with you.

Mark426 11/12/2008 06:40 AM

I had similar results, esp CA. My CA tested 440 with salifert prior to sending my sample to AWT. The AWT test came back with a CA of 326?

Tested my water again:
Salifert- 440-450
API - 450
LFS - 440 (dont know the brand of test)
ELOS - 460 (friends kit)

I dont know what is wrong with AWT. Several posts have confirmed that that their CA and PO4 tests are bogus.

gkyle 11/12/2008 07:06 AM

I think I'll just trust my own results and write this off as a bad experiment...

Boomer 11/12/2008 11:07 AM

If you have a need to send in water samples for testing send them here, about the same pice as AWT and they use " real" equipement. I have a couple of guys that are going to try them but have not heard from them yet.

http://www.labaquatics.com

I still do not trust AWT and they test Calcium with a ISE probe and then throw in a fudge factor to get their value. Their result always seen to suck. Last year a reef club sent in some split sample to ENC Labs, a real seawater testing lab and AWT and the results were not good. The issue with ENC is it is ~$40 / water parameter.


Silica (SiO2-3) ....................... High..................................0.7

They always seem to show high silica on all tests. First, this is not high. We like to see it 1 ppm or lower. NSW is around 2 ppm.

I also do not buy their PO4 either. They seem to always have big issues measuring PO4, Ca++ and Silica.

HowardW 11/12/2008 11:11 AM

Per AWT regarding test results for calcium:

" *These values represent only the amount of free calcium ions present in the samples. According to Randy Holmes-Farley, the
total calcium concentration can be 10% to 20% higher. "


As for the phosphate result, the few samples I sent in all came back with very low results similar to NSW levels. Maybe that sample somehow got contaminated or they just screwed up on that one. I would question them on it.

gkyle 11/12/2008 11:19 AM

Well, I sent a bit of a flame, and here is the response:

"I understand your frustration. Being a new customer, we had no previous tests to look at for the phosphate level…which was very high. I therefore re-tested your phosphate level myself, and the reading we got was confirmed in the second test. You may wish to take a critical look at your home kit, realizing that our test procedure is sensitive to more than one species of phosphate.
As for the calcium reading, there are distinct differences between electrochemical testing and titration-based testing. There are some excellent articles elucidating the differences and similarities that can be found on several of the online forums."

Boomer - thanks for the link, I'll try them out. Now I'm too curious not to...

Boomer 11/12/2008 01:31 PM

Yah gkyle, can you see all the flippin' spin they are giving you :lol:

Lutefisk 11/12/2008 01:38 PM

Quote:

<a href=showthread.php?s=&postid=13731453#post13731453 target=_blank>Originally posted</a> by Boomer
If you have a need to send in water samples for testing send them here, about the same pice as AWT and they use " real" equipement. I have a couple of guys that are going to try them but have not heard from them yet.

http://www.labaquatics.com

FYI - Shipping on "The Elements" $59.95 test is $19.86 to Florida

Boomer 11/12/2008 01:44 PM

Thanks Lute.

I had not really cheked on that"shipping' . That it staring to get pricey. As far as some tracking goes, it appears this is a Canadian based company, that is part of a large chemical and analytical supply company like Cole-Pamer. I had a kink but some how lost it.

gkyle 11/12/2008 01:44 PM

I could deal with it if my photometer read .01 and theirs said .04, but 1.24? No way. I felt compelled to return a small essay, but now it's time to vote with my feet, as they say. The Lab Aquatics site looks pretty good based on the sample report they provide. At least it shows a phosphate level of .03 or so, which would be a -1.21 at the other place :-)

Boomer 11/12/2008 01:47 PM

Ok I found them :)

http://www.seadsolutions.com/index.html

kaskiles 11/12/2008 02:02 PM

Ugh, it's like cable... To get the 7 channels I want, I have to buy two different packages, getting 38 unwanted channels... Some of them twice :)

I guess that $20 shipping ensures the water doesn't degrade much before testing.

Boomer 11/12/2008 11:45 PM

That is a great analogy for losts of things :lol:


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