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How to Hotrod your Alk Test

Mr. Ugly

Mr. Ugly

Past President
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Alk is one of the most important tank chemistry parameters to keep stable and in range. If you're tired of expensive inaccurate low precision alk tests, here's some cool geek stuff you can do.


- Use a Salifert 1ml syringe and tip for titration instead of the dropper bottle with the big fat drops. Did I say BIG FAT DROPS?

- Use a 5ml syringe for taking your water sample.

- Calibrate your test kit against the frag swap 3.8 meq/l alk reference standard.


Using the API alk test as an example...


Assemble the 1ml syringe, shake the hell out of your API test reagent, draw up 1 ml of reagent.

Usinng the other syringe, put 5ml of the alk reference standard into a large Salifert style vial.

Titrate until green to green/yellow.

Divide 3.8 by the volume used to get the conversion factor for meq/l per volume of reagent used.

So if it took .42 ml of reagent to titrate the reference standard, then: 3.8/.42 = 9.047 meq/l per ml of reagent used.

Now whenever you want to test your tank water, get 5ml of water, titrate as before, multiply the amount of reagent used by your conversion factor to get your alk reading.

For example, you find that it takes .33ml of reagent to titrate your water sample. .33ml X 9.04 meq/l/ml = 2.99 meq/l alk

If you don't want to multiply to figure your alk every time you test, use Excel to make up a chart so you can just look up your alk reading based on amount of reagent used.


hth!

:D
 
Thanks Norm, this sounds better than doubling up on tests like I usually. Is Salifert like API where 1 drop = 1 dKH?

I figured this was a more appropriate place to discuss my alk results rather than the DBTC thread so here it goes.

Ok, my only option was an API alk test. I tested the control and it came out to dKH of 10 or 3.6 mEq/L if I'm doing my calculations right (dKH/2.8=mEq/L). My water came out at 11 dKH or 3.9 mEq/L. So adjusting for test kit variance I should be at 4.1....... ok, I admit it, I was in the low 2's before I adjusted my alk last night :) That's what I get for not testing for like..... 2 months ( blushing ). In my defense I've made time to do about 15% water changes every week.... well know now at least test my alk when I do my water changes. Thanks guys, hopefully this will give the acan and the chalice a fighting chance.
 
Norm, nice write up, and a great technique - elimates the variation in volume of each drop. It seems like the alk tests can have a large amout of discrepancy between different makes, this would be a nice way to calibrate each batch/kit.

Since I wasn't able to make it to the swap - is there a way I get some of the alk ref soln?

Another thing - I use alk test kits to mostly monitor trends in alk, to avoid swings in alk. The absolute measurement is important to me, but avoiding a big day to day swing, esp when dialing in two part or a calcium reactor, is just as important, if not more so.
 
Very nice, Norman. I should try that. By the way, at the frag swap I recieved 3 bottles from the club. The two bottles were providine and alk. I could not read the label on the third bottle? What is in the third bottle?
 
Yep, 3rd was refractometer standard for checking your calibration.

Perry/vapormd, I have more alk standard. Can you pick it up in Alameda? We can meet, or I can leave some for you at Steve's.
 
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