Ditto
Valuable Member
Ok, was it reading ok then just stop? How long have you had the unit before it started doing this?
KH Director discrepancy
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Unfortunately, the KH Director is a laboratory grade device that requires laboratory grade calibration. That being said, once you get it there, it works very well.
How do you know its calibrated correctly? Well, you can look at how much waste is collected. If it doesn't add up correctly, something was not calibrated precisely. Its not written anywhere, but you can monitor the pumps as they operate. For my setup that has a sample tube and filter volume of 40ml and sample size set to 65ml, it performs as follows:
1. The sample pump will pull in volume + 12ml to prep the test chamber. 52ml for me.
2. The waste cannot be measured by pump and only puts out about 10ml. (If you manually run the pump, you can squeeze out the 1-2ml of fluid that I believe is the wetness of the initial rinsing)
3. Then the sample pump pulls in sample volume. 65ml for me.
4. Then the reagent pump pulls 1-2ml
5. The waste pump dumps everything
6. The sample pump reverses and empties the sample tube volume
In the end you should have wasted 12 + sample volume + reagent volume. Or for me 12 + 65 + ~2 or 79ish.
My issues with precise calibration was with the sample tube and filter volume. The sample tubing was not fully emptying at the end of the cycle so I was ending up with extra sample water. The culprit is the filter. Depending on how it is installed will change the volume it accounts for. Its best to install vertically.
I found that the best way to calculate the volume is to measure it.
1. Unplug the sample tube from the KH Director
2. Run the sample pump until it is dumping water. (Simulates the initial draw)
3. Then calibrate the pump (might as well)
4. Then run the pump in reverse with the other end of the sample tube now into a graduated cylinder until its out of water. This simulates the clearing of the sample tube. That volume is the sample tube and filter volume. Your thinking why can't I just run the pump forward into a graduated cylinder to get the volume? Its because the direction of the filter will effect its ability to be vacated.
How do you know its calibrated correctly? Well, you can look at how much waste is collected. If it doesn't add up correctly, something was not calibrated precisely. Its not written anywhere, but you can monitor the pumps as they operate. For my setup that has a sample tube and filter volume of 40ml and sample size set to 65ml, it performs as follows:
1. The sample pump will pull in volume + 12ml to prep the test chamber. 52ml for me.
2. The waste cannot be measured by pump and only puts out about 10ml. (If you manually run the pump, you can squeeze out the 1-2ml of fluid that I believe is the wetness of the initial rinsing)
3. Then the sample pump pulls in sample volume. 65ml for me.
4. Then the reagent pump pulls 1-2ml
5. The waste pump dumps everything
6. The sample pump reverses and empties the sample tube volume
In the end you should have wasted 12 + sample volume + reagent volume. Or for me 12 + 65 + ~2 or 79ish.
My issues with precise calibration was with the sample tube and filter volume. The sample tubing was not fully emptying at the end of the cycle so I was ending up with extra sample water. The culprit is the filter. Depending on how it is installed will change the volume it accounts for. Its best to install vertically.
I found that the best way to calculate the volume is to measure it.
1. Unplug the sample tube from the KH Director
2. Run the sample pump until it is dumping water. (Simulates the initial draw)
3. Then calibrate the pump (might as well)
4. Then run the pump in reverse with the other end of the sample tube now into a graduated cylinder until its out of water. This simulates the clearing of the sample tube. That volume is the sample tube and filter volume. Your thinking why can't I just run the pump forward into a graduated cylinder to get the volume? Its because the direction of the filter will effect its ability to be vacated.
arvind
Active Member
arvind
Active Member
I bought it used from a known source and first time trying to configure. I don't doubt if it is working. It has been consistent in its reading. Just that it doesn't show correct reading. Which I suspect that my configuration is somewhere off.
arvind
Active Member
Didn't think about measuring the waste water. Let me try that and report back. Btw I did measure the volume pulled by the sample tube using a graduated cylinder. That showed 21ml and if I measured the tube length it gave me 24ml. It didn't make a difference in the kh reading either way.
Did you take into account the 4.7inches of the beige pump tube...adds 1.5ml to the calculation. Either way, your best off measuring the volume. Additionally, after a couple of weeks of it running and wearing in, it should be recalibrated.
Fisherman Joe
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The only thing I do, is carefully calibrated your dosing pumps, as accurately as you can. If it’s 3.4ml dosed in 1min then put that, don’t put 3.0ml, After that calibrate the pH probe. After you have calibrated the pH probe it will give wacky readings for a few hours. I usually flush it a few times then leave it and run 2-3 tests.
After all this there may still be some discrepancies you can account for so then I run the reference solution and offset the results to match this. You KNOW the alkalinity of the reference solution. For me, I had to add 10% to the result.
Also, don’t forget getting the two different testing systems to match 100% isn’t the goal. You need to get the KH Director within an acceptable accuracy limit and then it will do the work. I set me dKH to 8.0in order to slow the growth of undesirable algae a little more. In truth My tank could be 7.8 or 8.2, it doesn't matter. The KH Director will keep it there. That’s all you need.
Stability. Your corals will adapt and thrive at whatever it is set too. It just needs to stay there.
After all this there may still be some discrepancies you can account for so then I run the reference solution and offset the results to match this. You KNOW the alkalinity of the reference solution. For me, I had to add 10% to the result.
Also, don’t forget getting the two different testing systems to match 100% isn’t the goal. You need to get the KH Director within an acceptable accuracy limit and then it will do the work. I set me dKH to 8.0in order to slow the growth of undesirable algae a little more. In truth My tank could be 7.8 or 8.2, it doesn't matter. The KH Director will keep it there. That’s all you need.
Stability. Your corals will adapt and thrive at whatever it is set too. It just needs to stay there.
arvind
Active Member
An update: I got it all figured out. It seems the water volume math was wrong all along. I got a 10$ weighing scale from amazon and measured the water and used that number for each calibration. This brought me the kh values closer to Hanna with a .2 difference. Previously the difference was 2 to 3!
What I am baffled by is the difference in volume between different methods of calculating it. For example, for the sample water, when I measure it by the length of the tubing times the width of the tube, it gave 24ml. When I emptied the water into a cup and measured it using a graduated cylinder it gave me 21ml. Yesterday when I measured it using a scale, it showed me 17.7. I do not think the difference can be this big between measuring the volume vs weight. It is probably salt creep etc that is forming in the tube that affects the calibration.
In addition to measuring the sample water, I also did a calibration for all three pumps by weighing the water. Then once I put everything back together, the numbers came back are far more accurate. I ran the test three times so far. Twice last night and once earlier today. It hasnt changed since. I will continue to run the tests this way for a while, double checking triple checking. I still haven't received the reference solution and i will be testing against it regardless.
Thanks for all your pointers, much appreciated.
@arking_mark measuring the waste water did not give the same results you got. I had 100ml for sampling and I got waste water of 104.2ml. Thinking this through, this could be an effect of using the wrong calibration in the first place.
What I am baffled by is the difference in volume between different methods of calculating it. For example, for the sample water, when I measure it by the length of the tubing times the width of the tube, it gave 24ml. When I emptied the water into a cup and measured it using a graduated cylinder it gave me 21ml. Yesterday when I measured it using a scale, it showed me 17.7. I do not think the difference can be this big between measuring the volume vs weight. It is probably salt creep etc that is forming in the tube that affects the calibration.
In addition to measuring the sample water, I also did a calibration for all three pumps by weighing the water. Then once I put everything back together, the numbers came back are far more accurate. I ran the test three times so far. Twice last night and once earlier today. It hasnt changed since. I will continue to run the tests this way for a while, double checking triple checking. I still haven't received the reference solution and i will be testing against it regardless.
Thanks for all your pointers, much appreciated.
@arking_mark measuring the waste water did not give the same results you got. I had 100ml for sampling and I got waste water of 104.2ml. Thinking this through, this could be an effect of using the wrong calibration in the first place.
Exactly what I had to do. I couldn't get it to read accurately at all when I used the "tube length" calc for sample volume. As soon I did the weigh method, boom, perfect results. GHL needs to take out the tube length calc and have everyone weigh the sample. Would save a lot of headaches.
Waste
For a 100ml sample, the waste volume should be sample volume + 12ml + reagent used. So minimally, you should see 112ml of waste volume. For me, for a 100ml sample it does ~3ml of reagent.
Now if you want some interesting discussion on dKH control...that's another headache. KH Director isn't an intelligent device and it took me a little while to really understand how it controls dosing.
arvind
Active Member
I understand. Because I was testing over and over again with various parameters I kept upping the sample volume as well and went all the way to 100ml which is the max volume. Didn't make much of a difference. Now that I have this all figured it out, I brought it down to 65ml same as you and is being consistent so far.
arvind
Active Member
Yes, I hear the Kh control is going to be major challenge. I have been reading about it in the manual. It looks like GHL has given several dials and knobs for you to play with so you can customize to your heart's content. As a result, setting it right can get tricky. I am saving that battle for another day. I want to just monitor the kh for a while and get comfortable with the system first.
Actually, the dKH control has almost no dials. Add On and Adaptive are essentially the same in my book, as I undertsnad them. One uses a volume and the other a percentage. Neither is intelligent. I've been noodling how to set it up and haven't settled on a good way to do it yet. I'm actually leaning to letting it measure and replace used alk 6 times a day.
I'm using the Triton method of dosing, but also doing incremental AWC.
Triton method is tied directly to alk. Dose Triton to keep alk at 8dKH and don't do water changes. Basically, Triton replenishes everything.
I'm not sold on the don't do water changes, but it allows me to feel comfortable will minimal water changes. I have my tank at 8dKH.
To raise my dKH by 1, requires 50ml of Triton (it's diluted). So I think I'm going to set the dosing at 0 and let the KH Director replace what is lost 6x a day but limit the max change by .25dKH. So if the reading is 7.9dKH it will add 5ml (dosing is set to happen right after measurement). If the reading is greater than 8 it will dose 0. As long as the system is consuming less then .25dKH every 4 hours, this should keep a pretty tight bound on the alk. It should essentially never go above 8 alk. If I want the average alk to be slightly above 8, I can just raise the target alk to 8.1. If something goes wrong with measurements, I have the alarm set for a reading of +- .5dKH. So worse case scenario, my alk goes up or down by .5dKH in a day, which is completely acceptible.
If you know your daily consuption and do the math, you're actually better off incrementally dosing a constant amount without the controller adjusting the dosing amount. The constant amount smoothes out the changes in consuption throughout the day and makes your alk average very close to 8. The add on or adaptive control will always be playing catch up with my method.
I'm using the Triton method of dosing, but also doing incremental AWC.
Triton method is tied directly to alk. Dose Triton to keep alk at 8dKH and don't do water changes. Basically, Triton replenishes everything.
I'm not sold on the don't do water changes, but it allows me to feel comfortable will minimal water changes. I have my tank at 8dKH.
To raise my dKH by 1, requires 50ml of Triton (it's diluted). So I think I'm going to set the dosing at 0 and let the KH Director replace what is lost 6x a day but limit the max change by .25dKH. So if the reading is 7.9dKH it will add 5ml (dosing is set to happen right after measurement). If the reading is greater than 8 it will dose 0. As long as the system is consuming less then .25dKH every 4 hours, this should keep a pretty tight bound on the alk. It should essentially never go above 8 alk. If I want the average alk to be slightly above 8, I can just raise the target alk to 8.1. If something goes wrong with measurements, I have the alarm set for a reading of +- .5dKH. So worse case scenario, my alk goes up or down by .5dKH in a day, which is completely acceptible.
If you know your daily consuption and do the math, you're actually better off incrementally dosing a constant amount without the controller adjusting the dosing amount. The constant amount smoothes out the changes in consuption throughout the day and makes your alk average very close to 8. The add on or adaptive control will always be playing catch up with my method.
arvind
Active Member
hey thanks for your insights. I guess i have to start playing with it sooner than later. can't wait!
Member No 1
Well-Known Member
Correct me if I'm wrong, but Add On is a fixed amount that the user programs in. Adaptive is just that, it adds a percentage up to a user defined maximum to adjust the dose amount.
Mine is set to adaptive, and it holds my dKh between 8.9-9.1. When the dKh value needs to be adjusted, I have looked at the amount being dosed, and it does increase/decrease by the correct percentage.
I run 6 80ml tests daily.
Mine is set to adaptive, and it holds my dKh between 8.9-9.1. When the dKh value needs to be adjusted, I have looked at the amount being dosed, and it does increase/decrease by the correct percentage.
I run 6 80ml tests daily.
They actually both work the same as far as I can tell.
Add on settings and adaptive settings have essentially the same parameters set. In one case its volume and in the other a percentage change.
In Add on control, you set a volume to change based on a dKH difference. So you can set a 50ml change for a 1dKH difference. If your reading is 1dKH lower than the set point, it will add 50ml. If you reading is .1 dKH lower than the set point it will add 5ml.
In Adaptive mode, you set a % change based on a dKH difference. So you can set a 50% change for a 1dKH difference. If your reading is 1dKH lower than set point, if will increase your dosage by 50%. If your reading is .1dKH lower than set point it will increase your dosage by 5%.
Both let you set and min/max amount that can be done and neither change your base dosing amount.
The real question is how do you use this control effectively?
According to @Randy Holmes-Farley, "Normal alk consumption is 0.5 to 4 dKH per day. Even a soft coral tank can use 2 dKH per day."
I guess its not surprising that Triton method starts you off with a .5dKH dose and has you adjust from there.
So maybe the best approach is to set your dosage for that minimum and then use my approach of setting the control adjustment based on the actual amount of dKH your reagents provide.
I like easy numbers and a 4 hour dosing schedule (6x per day). For my diluted Triton reagents, a 48ml dose will raise my alk by 1. So my settings would be:
Doser: 4ml, 6 times a day for 24ml or .5dKH replacement
Add on control:
1dKH deviation for 48ml dosage change
Min/max set to 28ml.
This would essentially enable me to set it and forget it.
Only concern would be an anomalous dKH reading could dump an extra .5dkh at once. So maybe limit the min/max and just increase the min/max or nominal dose if the system can't keep up.
Add on settings and adaptive settings have essentially the same parameters set. In one case its volume and in the other a percentage change.
In Add on control, you set a volume to change based on a dKH difference. So you can set a 50ml change for a 1dKH difference. If your reading is 1dKH lower than the set point, it will add 50ml. If you reading is .1 dKH lower than the set point it will add 5ml.
In Adaptive mode, you set a % change based on a dKH difference. So you can set a 50% change for a 1dKH difference. If your reading is 1dKH lower than set point, if will increase your dosage by 50%. If your reading is .1dKH lower than set point it will increase your dosage by 5%.
Both let you set and min/max amount that can be done and neither change your base dosing amount.
The real question is how do you use this control effectively?
According to @Randy Holmes-Farley, "Normal alk consumption is 0.5 to 4 dKH per day. Even a soft coral tank can use 2 dKH per day."
I guess its not surprising that Triton method starts you off with a .5dKH dose and has you adjust from there.
So maybe the best approach is to set your dosage for that minimum and then use my approach of setting the control adjustment based on the actual amount of dKH your reagents provide.
I like easy numbers and a 4 hour dosing schedule (6x per day). For my diluted Triton reagents, a 48ml dose will raise my alk by 1. So my settings would be:
Doser: 4ml, 6 times a day for 24ml or .5dKH replacement
Add on control:
1dKH deviation for 48ml dosage change
Min/max set to 28ml.
This would essentially enable me to set it and forget it.
Only concern would be an anomalous dKH reading could dump an extra .5dkh at once. So maybe limit the min/max and just increase the min/max or nominal dose if the system can't keep up.
arvind
Active Member
I plan to set it up this weekend and this explanation greatly helps.
arvind
Active Member
Another question for all KH Director users: how often do you calibrate the ph probe? GHL recommends once month. Do we really have to calibrate that often? Are there any signs to look out for other than the KH reading itself?
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