I have two of these and would be nice to buy the Reagent in larger volume - I figure it is some type of standard acid. Any of you smart people figure out an alternative yet?
Thanks!
Thanks!
KHG DIY or Alternative Reagent
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Randy Holmes-Farley
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It is easy to figure out the titrant (or, in any case, any mineral acid will do), but you also need to know the exact concentration, which we usually do not.
FWIW, it is easy to DIY the whole tset if you have a pH meter:
A DIY Alkalinity Test: By Randy Holmes-Farley - REEFEDITION
https://www.reef2reef.com/blog/a-diy-alkalinity-test-by-randy-holmes-farley
FWIW, it is easy to DIY the whole tset if you have a pH meter:
A DIY Alkalinity Test: By Randy Holmes-Farley - REEFEDITION
https://www.reef2reef.com/blog/a-diy-alkalinity-test-by-randy-holmes-farley
OP
OP
Very good, thank you. So if I follow the above test using the KHG reagent to say a standard solution 8 dkh to figure out the volume of reagent to drop ph to 4.5 and then through trial and error using that volume to come up with the concentration using mineral acid/rodi mix? Do you think that is feasible ?
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Randy Holmes-Farley
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I cannot really see why you would want to do that, rather than just use the DIY method instead, but yes, it will work. The DIY method alone will be as accurate or more accurate than using it to determine how much acid to use in a different method since you are adding the DIY uncertainty/error to the other kit uncertainty/error.
OP
OP
Perfect thanks for the Info. I want to do this because I want to continue to use the KHG as it is automated and I made the investment, however, I want to make my own reagent in a larger volume cheaper vs the expensive 1500ml current reagent X2 which runs out every 2 months and cost 30 a month to run two units. Thanks!!!
Randy Holmes-Farley
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Ah, I didn't realize you intended to use it in a KHG automatic titrator. I'd use only hydrochloric or sulfuric acid in that case.
How do you know how much volume it uses for each titration?
Do you know that standard acids are a lot cheaper than this reagent?
How do you know how much volume it uses for each titration?
Do you know that standard acids are a lot cheaper than this reagent?
OP
OP
1. Yes I have two KHG guardian units.
2. it is easy to measure, but why is that necessary to know? The current reagent is a packet that mixes up with 1500ml of water to produce 2 mos of reagent. The idea is to use a standard 8dkh solution, say 1 cup, and the current khg reagent to drop to 4.5 say that volume is 5 ml for example. Then I find the concentration of sulferic acid/rodi by adjustment that will drop 8 dkh to 4.5 with 5 mL of the solution that I just mixed. That would then be my alternative concentration that I can say make a gallon of reagent hands off for 4 months hopefully cheaper.
3. still gathering requirements so it may or may/not, theory is that DIY solution is cheaper than the current retail reagent.
2. it is easy to measure, but why is that necessary to know? The current reagent is a packet that mixes up with 1500ml of water to produce 2 mos of reagent. The idea is to use a standard 8dkh solution, say 1 cup, and the current khg reagent to drop to 4.5 say that volume is 5 ml for example. Then I find the concentration of sulferic acid/rodi by adjustment that will drop 8 dkh to 4.5 with 5 mL of the solution that I just mixed. That would then be my alternative concentration that I can say make a gallon of reagent hands off for 4 months hopefully cheaper.
3. still gathering requirements so it may or may/not, theory is that DIY solution is cheaper than the current retail reagent.
lnevo
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Any result from your attempts? I'm considering picking one of these up, but with the price drop and I've seen it said discontinued on one site and on an ebay ad that it was coralvue clearance. I'd snatch one up if the reagent can be recreated. Also the $35 a month per 45 day expense adds up.. well worth it, but if I'm paying more than is needed if something can be gotten in bulk, well that bit helps 
Randy Holmes-Farley
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If it is 0.1 N acid, I think the best bet is to just buy it (it is readily available from many sources including Hanna). I doubt it can be made DIY appreciably cheaper, although one could be 1 N or higher and dilute it to save money if you want.
coralbeauties
Valuable Member
Any updates on this? A guy in our local club is using muratic acid to make reagent for his alkatronic.
Jeff
Jeff
coralbeauties
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I played around with making my own reagent. I made up some fresh reagent with guardian reagent and measured the ph of the solution. I then measured out 1500g of water and added muratic acid till I got the same ph. I used 31.5% acid that I got from the paint department at lowes. It ended up using 5.5ml of acid. It took about 4 tests to run my original reagent out and start using the diy reagent. It tested at .7dkh lower then the oem stuff. I will let it run for a couple of days and adjust the calibration to match my salifert and hanna checker. If it works out this should save about $17 a month.
Jeff
Jeff
ihavecrabs
2500 Club Member
Hmm interesting. 0.7 seems like a pretty decent swing. Did you measure by weight or volume for total water?
coralbeauties
Valuable Member
weight for the water. In the settings you are able to increase or decrease what the guardian reads. so you can change the basic readings to match your test kits and it should read properly after that. should be able to readjust it like that for each batch.
Jeff
Jeff
ihavecrabs
2500 Club Member
I feel that would throw the accuracy of the test off given it is programmed to a specific acidity of titrant. My brain is working on half cylinders at the moment so sleep and then coffee might help me make more sense of this. Maybe not though!
coralbeauties
Valuable Member
within the system setup there is a line to adjust kh. So what I did was run a test with the guardian and a test with my hanna checker. If the guardian is .5 lower then the hanna you enter +.5 into the adjust kh line and save the settings. The next test will be dead on with the hanna readings. Reading the manual it warns against using any diy reagent that might damage the components in the mixing chamber. I dont know for sure but from what I have read the tests use an acid based reagent to measure the ph change within the chamber after each drop so I have to wonder how this diy method would be any different. When I cut open my oem guardian reagent some of it got on my scissors and stained them pretty bad so it must be fairly strong stuff. I guess the worst case would be I have to replace the mixing chamber and possibly the ph probe. worth the gamble.
Jeff
Jeff
