reefnjunkie Posted October 2, 2014 Share Posted October 2, 2014 This was copied from a post Madmike put up...... The best alk testing is doing your own acid titration down to a ph of 4.2, super accurate and super cheap because you have to buy the acid by the gallon so you will have enough for years of use . Initial investment is a ph meter and the gallon of acid...good for years of testing! here is a clip from rc chemistry guys You can buy 0.1 N Sulfuric acid standard used as the titrant from: http://www.grainger.com/Grainger/items/4YNA6?cm_mmc=Google%20Base-_-Test%20Instruments-_-Laboratory%20Supplies-_-4YNA6[/url] also sells 0.1 N sulfuric acid standards. It may be best to calibrate your pH meter using a 4 & 7 standard before you start the test. Easy part; Testing Now take a sample of your aquarium water, you can use any volume but I like to use 100ml because my pH meter sits nicely in the cup without me holding it at this level. Stick in your pH meter to your sample. You should get the same reading you do when you stick it directly in your tank. If not start over with a clean sample container. Now draw up some 0.1 N HCl solution in to your 5ml syringe. And start dropping into your sample 0.5 mls at a time and watch your pH meter. You are adding a strong acid so your pH should fall rapidly. Once your pH hits 5 start to slow down and add a drop at a time until your pH hits 4.2 . The reason we are shooting for 4.2 is because this is the point where all available carbonates have been converted to carbonic acid. You would think this would be pH 7 but it's not as carbonic acid is a weak acid and you have to really saturate it etc. Anyway, once you have reached pH 4.2 you are done and now can calculate your total alkalinity. Alk mg of CaC03 /L = A x N x 50,000 / mL of sample Where A = ml of acid added N = normality of your HCL So if you added 4ml of 0.1 HCL before you hit a pH of 4.2 4*0.1*50,000 / 100 = 200 ppm CaC03 equivalents or your total alkalinity is 4 meg/L (mg/L / 50 = meg/L). The above information was taken and corrected from this thread: http://www.reefcentral.com/forums/sh...ion+alkalinity Randy provides further details in this article: What is Alkalinity http://www.advancedaquarist.com/2002/2/chemistry __________________ Cliff Babcock 1 1 Quote Link to comment Share on other sites More sharing options...
reefnjunkie Posted October 2, 2014 Author Share Posted October 2, 2014 Nurnberg Scientific near Johns Landing carries the sulfuric acid Quote Link to comment Share on other sites More sharing options...
Micah Posted October 2, 2014 Share Posted October 2, 2014 I love that place. Cheap pH calibration solutions as well. 8 bucks for WAY more than you'd ever need. Oh, and cool article! Quote Link to comment Share on other sites More sharing options...
LC Scott Posted October 2, 2014 Share Posted October 2, 2014 I love that place. Cheap pH calibration solutions as well. 8 bucks for WAY more than you'd ever need. Oh, and cool article! They are right around the corner from me. I'm going to stop in in the morning. Sent from my Prism using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
reefnjunkie Posted October 2, 2014 Author Share Posted October 2, 2014 I get about 1400 tests for 40.00 with no color guessing basiclly you take 100mls of tank water, put the PH Probe in that water and add the acid until the PH gets to 4.2. You then multiply the mls used by 2.8 and thats your KH I use 2.8mls of acid times 2.8 gives me a KH of 7.84 easy peezy Quote Link to comment Share on other sites More sharing options...
LC Scott Posted October 2, 2014 Share Posted October 2, 2014 Anyone want to to split a gallon? Sent from my Prism using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
LC Scott Posted October 20, 2014 Share Posted October 20, 2014 Ordered a qt. of acid from Nuremberg scientific, didn't want to order a gallon and find out I hate this test. Gallons are $55 and qt. are $23 Quote Link to comment Share on other sites More sharing options...
TheClark Posted October 20, 2014 Share Posted October 20, 2014 Proven SPS guru posts how to monitor KH. Yeah, that has my attention for sure, thanks for reposting this is such cool tip. Quote Link to comment Share on other sites More sharing options...
reefnjunkie Posted October 21, 2014 Author Share Posted October 21, 2014 FWIW- I have the Red Sea Pro test kit (puke) for Mg, Ca and KH, I bought it to test water for a few tanks I take care of and its whats they use themselves. Well after cussing out that stupid KH test kit for the past 2 months I decide to bring a water sample home to test against the titration. Titration test KH 8.24 maybe a little less Red Sea HADNT EVEN BEGUN TO CHANGE COLOR UNTIL (sorry caps lock :() 9.4 and would have been what I called the correct color around 9.7ish Go Red Sea (rock2) (in the trash that is) actually I'll just subtract 1.2 from each reading to know what the real level is Quote Link to comment Share on other sites More sharing options...
LC Scott Posted November 13, 2014 Share Posted November 13, 2014 Sweet, just did my test for the first time, came p it to 7.8 using reefjunkies formula. 1 Quote Link to comment Share on other sites More sharing options...
TheClark Posted November 13, 2014 Share Posted November 13, 2014 Ordered a qt. of acid from Nuremberg scientific, didn't want to order a gallon and find out I hate this test. Gallons are $55 and qt. are $23 Thanks for that info, might have to order some up! Quote Link to comment Share on other sites More sharing options...
TheClark Posted February 7, 2015 Share Posted February 7, 2015 (edited) This technique is making the news over at R2R as Randy Holmes Farley did a writeup. Just think, we had it here first, thanks reefnjunkie! My 0.1N acid came today. Like the kid in Christmas Story I rushed up to unwrap it and to the titration test. So I heard this rumor, a rumor that Hanna measures 18% low on alkalinity. So I have been subtracting 18% from it's ready to get to my target (7-8 dkh). Results: 9.24 Hanna (with the 18% adjustment I was thinking, around 7.6, perfect!) 10.64 Titration Uh oh.. Crud! Hanna is less than actual, not 18% more?? I have been higher than I thought the whole time?? Ugh. Time to bust out the SF test and have yet a third number. So 10.64, too high? Higher than I was shooting for... Edited February 7, 2015 by theclark Quote Link to comment Share on other sites More sharing options...
TheClark Posted February 7, 2015 Share Posted February 7, 2015 SF tells me I am at 9.3, almost identical to Hanna. Who knows??!! I know, stability is key. Well it was too fun not to try. Anyone want to buy some 0.1N acid?? Quote Link to comment Share on other sites More sharing options...
TheClark Posted February 7, 2015 Share Posted February 7, 2015 I almost forgot one more thing The reef to reef article says to stop adding acid at 4.5 instead of 4.2 I repeated the test and stopped at 4.5 It came out to 9.5, right inline with sf and hanna Quote Link to comment Share on other sites More sharing options...
reefnjunkie Posted February 7, 2015 Author Share Posted February 7, 2015 (edited) I almost forgot one more thing The reef to reef article says to stop adding acid at 4.5 instead of 4.2 I repeated the test and stopped at 4.5 It came out to 9.5, right inline with sf and hanna I posted a question to Randy Holmes about using 4.2 and he said he almost mentioned using 4.2 vs 4.5 and that the difference between the two is nominal-either works-but you may have seen that Edited February 7, 2015 by reefnjunkie Quote Link to comment Share on other sites More sharing options...
TheClark Posted February 7, 2015 Share Posted February 7, 2015 Nice, thanks! Love this hobby, so many aspects to it. My probe was all over the place and very slow to respond so I will probably stick to the more run of the mill tests in the future that I can be successful at. Completely enjoyed trying this out, good stuff! Quote Link to comment Share on other sites More sharing options...
Frank Posted February 7, 2015 Share Posted February 7, 2015 I have been using this method for awhile now. I add like 2.5ml and wait for the prob then adds drops till hits the mark. 1 Quote Link to comment Share on other sites More sharing options...
reefnjunkie Posted February 8, 2015 Author Share Posted February 8, 2015 Nice, thanks! Love this hobby, so many aspects to it. My probe was all over the place and very slow to respond so I will probably stick to the more run of the mill tests in the future that I can be successful at. Completely enjoyed trying this out, good stuff! The slow response of the probe may be a sign the probe needs to be replaced- a good test is seeing how long it takes to settle when you calibrate it. I had the same results before replacing a year old probe- the new probe jumps from the tanks PH to the lower PH in about 10 seconds or less and doesn't bounce around. I'm sure you're mixing the water/solution well too-right LOL 2 Quote Link to comment Share on other sites More sharing options...
TheClark Posted February 8, 2015 Share Posted February 8, 2015 Ah good point. I wonder if a standalone probe would work like those 20 dollar Amazon ones.... Hmmmm Quote Link to comment Share on other sites More sharing options...
LC Scott Posted February 9, 2015 Share Posted February 9, 2015 I was runningm side by side test but I have grown confident in the results, I also have enough pH calbation fluid for the next few years. Quote Link to comment Share on other sites More sharing options...
TheClark Posted June 25, 2015 Share Posted June 25, 2015 I wonder if this is something that could be automated? If someone could help with the mechanical aspects, I would do the software... Quote Link to comment Share on other sites More sharing options...
Blue Z Reef Posted June 25, 2015 Share Posted June 25, 2015 I wonder if this is something that could be automated? If someone could help with the mechanical aspects, I would do the software... I think it would be possible but you'd need 2 accurate dosing pumps and a controllable dump valve. Pump one runs a set amount of time to fill container with tank water that has probe in it. Pump two runs acid in intervals waiting for the probe to catch up. Once reaching set point, record number of intervals. Run calculation Display results Dump container with valve into waste reservoir Pump one turns on to submerge probe again. May need a rinse program. The issue is going to be keeping everything calibrated properly for the acid dose. ...I'll keep waiting for the Mindstream to come out hehe Quote Link to comment Share on other sites More sharing options...
TheClark Posted June 25, 2015 Share Posted June 25, 2015 I think it would be possible but you'd need 2 accurate dosing pumps and a controllable dump valve. Pump one runs a set amount of time to fill container with tank water that has probe in it. Pump two runs acid in intervals waiting for the probe to catch up. Once reaching set point, record number of intervals. Run calculation Display results Dump container with valve into waste reservoir Pump one turns on to submerge probe again. May need a rinse program. The issue is going to be keeping everything calibrated properly for the acid dose. ...I'll keep waiting for the Mindstream to come out hehe Let's build it! This guy is taking a different approach to the problem, but the titration test seems much easier. He does address some of the items you bring up though Jeff in the thread. It is an interesting read. http://www.reefcentral.com/forums/showthread.php?t=2508211&page=5 Quote Link to comment Share on other sites More sharing options...
Frank Posted August 9, 2015 Share Posted August 9, 2015 Ran out of 0.1 N Sulfuric acid anybody wan to split some????? Quote Link to comment Share on other sites More sharing options...
LC Scott Posted August 10, 2015 Share Posted August 10, 2015 Ran out of 0.1 N Sulfuric acid anybody wan to split some?????Frank, I have almost a half gallon, I could part with some. Sent from my SGH-M919 using Tapatalk Quote Link to comment Share on other sites More sharing options...
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