I do think there is a resolution issue with over 75 test done I have never tested 7.5 DKH it always jumps from 7.4 to 7.6 even if the testing period is 15,40,60,120 or 240 min I have never tested @ 7.5. I have also noticed when the unit is testing and droping reagent that one drop does not always equal .1 DKH sometimes one drop jumps the DKH .2. It is not a big deal but I do feel that the resolution may be overstated and is actually between .1 and .2 DKH . I also played with testing a higher DKH tank and it would read 7.6,7.7 but not 7.8 dkh it always jumps to 7.9.
KH Guardian: Automatic Alkalinity Controller- My Experiences
- Thread starter Rick.45cal
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Rick.45cal
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I've noticed that sometimes a drop of reagent equals .2 dKH, I think that's a product of how much the pH changes in the sample as to what the change in dKH.
I've noticed all sorts of variations in readings on mine from .1 dKH to .2 dKH and .3dKH. It is interesting that you have never had a 7.5dKH reading. (I just checked my log I don't have one either). I have plenty of movement in .1 dKH though.
I've noticed all sorts of variations in readings on mine from .1 dKH to .2 dKH and .3dKH. It is interesting that you have never had a 7.5dKH reading. (I just checked my log I don't have one either). I have plenty of movement in .1 dKH though.
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Rick.45cal
2500 Club Member
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Rick.45cal
2500 Club Member
I'll be happy with it settling down around 7.5 dKH. I'm happy with my progress so far. My growth rates have increased drastically, so my dosing is gonna require some more adjusting but I'm getting there. I'm not too overly concerned about getting my alkalinity flat, while that would be ideal, I'm not sure it's a realistic goal. (Might be easier for you with the Dastaco reactor but consumption will always fluctuate).
I would be interested to know why neither of us has landed on 7.5 dKH though! In the grand scheme of things sample size is still very small!
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Rick.45cal
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You are indeed correct. Interesting observations.
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Rick.45cal
2500 Club Member
I wonder if you changed the setpoint to 7.6 or 7.4 if you still wouldn't get those numbers
If the raw value is accurate to 1/20th of a meq/L and you convert that to dKH (using 2.81 multiplier) and then round to 0.1 you get:
2.5 meq/l * 2.81 = 7 dkh
2.55 meq/l * 2.81 = 7.2 dkh
2.6 meq/l * 2.81 = 7.3 dkh
2.65 meq/l * 2.81 = 7.4 dkh
2.7 meq/l * 2.81 = 7.6 dkh
2.75 meq/l * 2.81 = 7.7 dkh
2.8 meq/l * 2.81 = 7.9 dkh
2.85 meq/l * 2.81 = 8 dkh
2.5 meq/l * 2.81 = 7 dkh
2.55 meq/l * 2.81 = 7.2 dkh
2.6 meq/l * 2.81 = 7.3 dkh
2.65 meq/l * 2.81 = 7.4 dkh
2.7 meq/l * 2.81 = 7.6 dkh
2.75 meq/l * 2.81 = 7.7 dkh
2.8 meq/l * 2.81 = 7.9 dkh
2.85 meq/l * 2.81 = 8 dkh
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Rick.45cal
2500 Club Member
That explains why there is no 7.1 dKH in my log either. I think you nailed it!
Using a Calcium reactor on my 500G loaded SPS Tank starting at lights on, which is overnight on this system, 10 PM to 6AM my Alk would fall from 8.6 to 8.2 based on consumption using hanna and salifert tests. During this same time KDH measures the fall 8.3 to 8.1 or 8.6 to 8.4 with .03 error correction. I agree that this unit has .2 to .3 of an error and not .1 as advertised unless my unit is defective. I opened a case and provided the data, the feed back thus far was to add error correction of .3. Unfortunately this still does follow the natural usage curve that I have seen for over a year in this system. Still working with Tech support and will keep you all posted....
Carlos@CoralVue
Active Member
I think most people need to remember that the variance is not only for the KHG but Hanna and Salifert also have a variance in testing. Hanna has a +/-5% of reading variance and Salifert has a 0.2dKH variance as well. So a reading of 8.6 dKH could have easily been 8.2-9 on Hanna and 8.4-8.8 on Salifert.
So are you saying that the KH is more accurate than those tests as it is advertised as a .1 of an error? If that is true why does my bounce from 8.6 to 8.7 to 8.3 to 8.6 to 8.7 and back to 8.2 hours apart. Those test kits with its advertised error do not swing like that. For example if I am checking with Hanna or Salifert during Lights the number continues to drop until lights out. KH bounces all over the place. Either this unit is defective or the error advertised in the below picture is not published correctly. Not trying to publicly say the product dose not work as advertised, but I feel that either my unit is defective or something else like there is an error in the reagent as I measured the water with a scientific scale? Thanks for your help!
TIME N/A W.161 KS=0D L%0 S%0 SW>_ERR KH :0.00
TIME N/A W.161 KS=0D L%0 S%0 SW>_ERR KH :0.00
02/16 09:32:54 Save New System Environment.
02/16 09:39:30 RESET !
02/16 09:45:05 W.161 KS=0D L%0 S%0 SW>_ERR KH :0.00
02/16 10:01:35 RESET !
02/16 10:02:49 Test KH doser
02/16 10:03:09 Test KH doser
02/16 10:03:33 Test KH doser
02/16 10:03:49 Test KH doser
02/16 10:04:21 Test KH doser
02/16 10:04:36 Test KH doser
02/16 10:04:55 Save New System Environment.
02/16 10:13:34 W.127 %1 L.K= 5.40C.K= 7.00 Try=1
02/16 10:22:55 W.128 %0 L.K= 5.40C.K= 8.10 Try=2
02/16 10:31:56 W.127 %0 L.K= 5.40C.K= 8.00 Try=3
02/16 10:49:19 W.125 %0 AK. 1.00 KH :8.10
02/16 11:00:37 Save New System Environment.
02/16 11:03:07 RESET !
02/16 11:13:13 W.125 %0 AK. 1.00 KH :8.30
02/16 10:23:16 W.125 %0 AK. 1.00 KH :8.00
02/16 10:43:24 W.125 %0 AK. 1.00 KH :8.00
02/16 10:45:54 Save New System Environment.
02/16 10:46:19 Save New System Environment.
02/16 10:48:55 Save New System Environment.
02/16 10:49:34 Save New System Environment.
02/16 11:02:13 W.125 %0 AK. 1.00 KH :8.00
02/16 11:06:32 Save New System Environment.
02/16 11:17:06 W.125 %0 L.K= 8.00C.K= 6.92 Try=1
02/16 11:26:10 W.124 %0 L.K= 8.00C.K= 8.62 Try=2
02/16 11:35:20 W.125 %0 L.K= 8.00C.K= 8.62 Try=3
02/16 11:49:53 Save New System Environment.
02/16 12:01:06 W.125 %0 AK. 2.77 KH :8.57
02/16 16:14:07 W.129 %0 AK.12.00 KH :8.47
02/16 18:13:58 W.130 %0 AK.12.00 KH :8.47
02/16 18:38:28 W.129 %0 AK.12.00 KH :8.47
02/16 18:43:21 Save New System Environment.
02/16 18:56:43 W.129 %0 AK.26.21 KH :8.57
02/16 19:34:01 Save New System Environment.
02/16 19:47:43 W.128 %0 AK.50.00 KH :8.40
02/16 20:51:57 W.129 %0 AK.50.00 KH :8.40
02/16 21:14:09 W.130 %0 AK.50.00 KH :8.50
02/16 21:52:35 Save New System Environment.
02/16 22:02:56 W.131 %0 AK. 0.00 KH :8.70
02/16 22:06:31 Save New System Environment.
02/16 22:17:36 W.132 %0 L.K= 8.70C.K= 8.10 Try=1
02/16 22:27:11 W.130 %0 L.K= 8.70C.K= 8.10 Try=2
02/17 00:04:24 W.133 %0 AK. 0.00 KH :8.10
02/17 00:54:56 W.132 %0 AK. 0.00 KH :8.30
02/17 02:31:29 W.131 %0 AK. 0.00 KH :8.30
02/17 03:52:48 W.132 %0 AK. 0.00 KH :8.30
02/17 04:51:20 W.131 %0 AK. 0.00 KH :8.10
02/17 06:04:43 W.133 %0 AK. 0.00 KH :8.30
02/17 06:18:33 Save New System Environment.
02/17 06:28:38 W.131 %0 AK. 0.00 KH :8.60
02/17 09:00:22 W.131 %0 AK. 0.00 KH :8.60
02/17 09:04:38 Save New System Environment.
02/16 09:10:02 Save New System Environment.
02/17 09:22:03 W.131 %0 AK. 0.00 KH :8.60
02/17 09:50:44 W.132 %0 AK. 0.00 KH :8.70
02/17 10:12:40 W.131 %0 AK. 0.00 KH :8.60
02/17 10:39:14 W.131 %0 AK. 0.00 KH :8.60
02/17 14:54:01 W.132 %0 AK.0.00 KH :8.40
02/17 19:08:56 W.133 %0 AK.0.00 KH :8.40
02/17 19:20:23 Save New System Environment.
02/17 20:41:13 Save New System Environment.
02/17 20:51:54 W.133 %0 AK. 0.00 KH :8.60
02/17 21:46:23 W.135 %0 AK. 0.00 KH :8.60
02/17 22:27:19 W.134 %0 AK. 0.00 KH :8.20
02/17 22:43:30 W.133 %0 AK. 0.00 KH :8.60
02/17 22:57:07 Save New System Environment.
02/17 23:08:38 W.134 %0 AK. 0.00 KH :8.70
02/18 00:37:34 W.134 %0 AK. 0.00 KH :8.70
So are you saying that the KH is more accurate than those tests as it is advertised as a .1 of an error? If that is true why does my bounce from 8.6 to 8.7 to 8.3 to 8.6 to 8.7 and back to 8.2 hours apart. Those test kits with its advertised error do not swing like that. For example if I am checking with Hanna or Salifert during Lights the number continues to drop until lights out. KH bounces all over the place. Either this unit is defective or the error advertised in the below picture is not published correctly. Not trying to publicly say the product dose not work as advertised, but I feel that either my unit is defective or something else like there is an error in the reagent as I measured the water with a scientific scale? Thanks for your help!
TIME N/A W.161 KS=0D L%0 S%0 SW>_ERR KH :0.00
TIME N/A W.161 KS=0D L%0 S%0 SW>_ERR KH :0.00
02/16 09:32:54 Save New System Environment.
02/16 09:39:30 RESET !
02/16 09:45:05 W.161 KS=0D L%0 S%0 SW>_ERR KH :0.00
02/16 10:01:35 RESET !
02/16 10:02:49 Test KH doser
02/16 10:03:09 Test KH doser
02/16 10:03:33 Test KH doser
02/16 10:03:49 Test KH doser
02/16 10:04:21 Test KH doser
02/16 10:04:36 Test KH doser
02/16 10:04:55 Save New System Environment.
02/16 10:13:34 W.127 %1 L.K= 5.40C.K= 7.00 Try=1
02/16 10:22:55 W.128 %0 L.K= 5.40C.K= 8.10 Try=2
02/16 10:31:56 W.127 %0 L.K= 5.40C.K= 8.00 Try=3
02/16 10:49:19 W.125 %0 AK. 1.00 KH :8.10
02/16 11:00:37 Save New System Environment.
02/16 11:03:07 RESET !
02/16 11:13:13 W.125 %0 AK. 1.00 KH :8.30
02/16 10:23:16 W.125 %0 AK. 1.00 KH :8.00
02/16 10:43:24 W.125 %0 AK. 1.00 KH :8.00
02/16 10:45:54 Save New System Environment.
02/16 10:46:19 Save New System Environment.
02/16 10:48:55 Save New System Environment.
02/16 10:49:34 Save New System Environment.
02/16 11:02:13 W.125 %0 AK. 1.00 KH :8.00
02/16 11:06:32 Save New System Environment.
02/16 11:17:06 W.125 %0 L.K= 8.00C.K= 6.92 Try=1
02/16 11:26:10 W.124 %0 L.K= 8.00C.K= 8.62 Try=2
02/16 11:35:20 W.125 %0 L.K= 8.00C.K= 8.62 Try=3
02/16 11:49:53 Save New System Environment.
02/16 12:01:06 W.125 %0 AK. 2.77 KH :8.57
02/16 16:14:07 W.129 %0 AK.12.00 KH :8.47
02/16 18:13:58 W.130 %0 AK.12.00 KH :8.47
02/16 18:38:28 W.129 %0 AK.12.00 KH :8.47
02/16 18:43:21 Save New System Environment.
02/16 18:56:43 W.129 %0 AK.26.21 KH :8.57
02/16 19:34:01 Save New System Environment.
02/16 19:47:43 W.128 %0 AK.50.00 KH :8.40
02/16 20:51:57 W.129 %0 AK.50.00 KH :8.40
02/16 21:14:09 W.130 %0 AK.50.00 KH :8.50
02/16 21:52:35 Save New System Environment.
02/16 22:02:56 W.131 %0 AK. 0.00 KH :8.70
02/16 22:06:31 Save New System Environment.
02/16 22:17:36 W.132 %0 L.K= 8.70C.K= 8.10 Try=1
02/16 22:27:11 W.130 %0 L.K= 8.70C.K= 8.10 Try=2
02/17 00:04:24 W.133 %0 AK. 0.00 KH :8.10
02/17 00:54:56 W.132 %0 AK. 0.00 KH :8.30
02/17 02:31:29 W.131 %0 AK. 0.00 KH :8.30
02/17 03:52:48 W.132 %0 AK. 0.00 KH :8.30
02/17 04:51:20 W.131 %0 AK. 0.00 KH :8.10
02/17 06:04:43 W.133 %0 AK. 0.00 KH :8.30
02/17 06:18:33 Save New System Environment.
02/17 06:28:38 W.131 %0 AK. 0.00 KH :8.60
02/17 09:00:22 W.131 %0 AK. 0.00 KH :8.60
02/17 09:04:38 Save New System Environment.
02/16 09:10:02 Save New System Environment.
02/17 09:22:03 W.131 %0 AK. 0.00 KH :8.60
02/17 09:50:44 W.132 %0 AK. 0.00 KH :8.70
02/17 10:12:40 W.131 %0 AK. 0.00 KH :8.60
02/17 10:39:14 W.131 %0 AK. 0.00 KH :8.60
02/17 14:54:01 W.132 %0 AK.0.00 KH :8.40
02/17 19:08:56 W.133 %0 AK.0.00 KH :8.40
02/17 19:20:23 Save New System Environment.
02/17 20:41:13 Save New System Environment.
02/17 20:51:54 W.133 %0 AK. 0.00 KH :8.60
02/17 21:46:23 W.135 %0 AK. 0.00 KH :8.60
02/17 22:27:19 W.134 %0 AK. 0.00 KH :8.20
02/17 22:43:30 W.133 %0 AK. 0.00 KH :8.60
02/17 22:57:07 Save New System Environment.
02/17 23:08:38 W.134 %0 AK. 0.00 KH :8.70
02/18 00:37:34 W.134 %0 AK. 0.00 KH :8.70
A good friend of mine is also prototyping the product and he is having the same results pictured below - he also has a large SPS farm. Any feedback on the bounce is appreciated.
Thanks!
Randy Holmes-Farley
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While I no nothing about the accuracy of this unit, and they may be overstating the true accuracy, I'm not sure how one can conclude it isn't measuring correctly just because there are small changes in the reported tank alkalinity, unless you somehow otherwise know what the alkalinity is.
Presumably these tanks get some sort of dosing at some time (maybe not in the times shown, but that isn't clear). Further, pH will impact the answer, and even a tiny but of calcium carbonate solid (perhaps from a fish stirring up some detritus, etc.) getting into the test will impact the results, as I show below:
Assume you are using 50 mL sample size (that's what I was told, but I don't independently know that).
A 1 mm diameter grain of calcium carbonate sand has a volume of 0.0005 mL and a weight of perhaps 0.0015 grams (1.5 mg). That means it contains 1.5 mg/100 mg/mmole = 0.015 mmole of CaCO3, which has twice that in alkalinity, or 0.03 meq of alk. Put that in 50 mL and the effective concentration is 0.6 meq/L (1.7 dKH).
Consequently, a much smaller grain of sand (or many really tiny bits of calcium carbonate) can readily impact the alkalinity that is measured if you are worrying about fluctuations on the order of 0.2 dKH.
Presumably these tanks get some sort of dosing at some time (maybe not in the times shown, but that isn't clear). Further, pH will impact the answer, and even a tiny but of calcium carbonate solid (perhaps from a fish stirring up some detritus, etc.) getting into the test will impact the results, as I show below:
Assume you are using 50 mL sample size (that's what I was told, but I don't independently know that).
A 1 mm diameter grain of calcium carbonate sand has a volume of 0.0005 mL and a weight of perhaps 0.0015 grams (1.5 mg). That means it contains 1.5 mg/100 mg/mmole = 0.015 mmole of CaCO3, which has twice that in alkalinity, or 0.03 meq of alk. Put that in 50 mL and the effective concentration is 0.6 meq/L (1.7 dKH).
Consequently, a much smaller grain of sand (or many really tiny bits of calcium carbonate) can readily impact the alkalinity that is measured if you are worrying about fluctuations on the order of 0.2 dKH.
Thank you!1000 is the largest value it will take.
Do you know the largest number "Tank Volume (L)" it will allow you to add? Basically trying to see if this will work on a large system.1000 is the largest value it will take.
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