Equipment question

[gilly]

Hi all

Two quick questions..(ive read thru all posts on this.. Just wanted an updated answer

1. Ive gone thru several ph meters.. Pinpoint . Aquacontroller 3 and milwakee combo ph/tds meters.... All of them eventually fail to calibrate.. And i always keep them wet. I was especially disappointed in the Aquacontroller 3..even after i bought a new probe.. Eventually failed to calibrate after 6 months.. And i kept it clean. Is there a better/more reliable ph meter model that i should be looking at? Mainly i just need to make sure my r/o tapwater mix for discus tank stays consistent without having to always use seachem neutral regulator... And also keep a close eye as i use muriatic acid to drop ph and try to induce spawning in wild discus

2. any recommendations on a spectrophotometeric nitrate test that works great. (one where just put tank water in cuvette and it gives an accurate reading. I guess it would need to be a low range one.. Ive scoured.. Looked at outside reviews on hanna, hach, etc.. But loys of variability... And again..i just wanted an updated experienced opinion from the group here

Thanks all for your time!

Gilly



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[Asmack Arabia]

hi gilly,

for the ph meter, i am using EXTECH, its around USD80 in Amazon and so far, its working fine. I just calibrated it the other day and its ok.

for the nitrate tester, i am using hanna bench photometer. i am not so happy on this one as I seem to get different results depending on how hard I shake the cuvette.

let me know what you plan to settle with.

[Tom Barr]

I've found the pinpoint american Marine to be good over the years.
Simple and easy to calibrate. The probes might need replacing every so often, but that's normal.
Once they fail to calibrate well and drift etc, then it's time to replace.

You can buy many different brands in the 400-600$ range that are research grade instruments, but I doubt you need that.
I would use acetic acid to reduce pH or peat, these are better as far as being natural products and much safer, easier to handle and purchase.
Milwaukee, I do not like.
For RO, a simple TDS meter works fine.

As far as a colorimeter, Hanna works if........like all colorimeters/spects, if and only if......you run a standard along with your sample. A 20,000$ beckman spect, we still have to run the standards.
So make some low range standards, say 1 ppm, 5 ppm and 10 ppm, maybe 1 liter's worth at a time and get a decent flask that's got a tight seal to minimize evaporation over time.
So you zero the colorimeter, add the blank, rezero, then run the standard. Then the second two point method with another standard of different ppm. Then run the sample.
Not much different/trouble vs running one sample.

You can make a more concentrated standard and dilute each time also, say make a 100 ppm, then dilute to make 50, 5.0 and 0.5ppm etc.
Then you can customize the range with the RO water dilution.

Up to you though.
I target the range I'm typically testing within.

[Asmack Arabia]

Hello Tom,

I would like to make a follow-up question to your reply. I would like to do exactly what you said about running a standard. I got lost when you said "zero the colorimeter, add the blank, rezero, then run the standard". How do you "rezero" and what "blank" do you mean?

I do follow exactly the instructions on my hanna iron colorimeter wherein I do run a sample first, then add the reagent on the sample, then run again. Is that what you mean? Sorry for being so novice...

[Tom Barr]

Hello Tom,

I would like to make a follow-up question to your reply. I would like to do exactly what you said about running a standard. I got lost when you said "zero the colorimeter, add the blank, rezero, then run the standard". How do you "rezero" and what "blank" do you mean?

I do follow exactly the instructions on my hanna iron colorimeter wherein I do run a sample first, then add the reagent on the sample, then run again. Is that what you mean? Sorry for being so novice...

You zero the blank/cuvette/water etc. You are telling the meter to ignore that................. and only measure the reacted sample.

Then you add your sample and reagents.

I run the standards 1st, say a 1ppm and 10 ppm.

Then I run the tank's NO3. In the tank is say 33 ppm at that point, then I'll run a known standard @ 30 ppm and see how close to the 30 ppm standard I am etc.
This ensures the validity of the test procedure.

[Asmack Arabia]

Thank you Tom. I will do as you said.