GHL KH Director KH control settings...

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Laith

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Hello all,

(I've also posted this on the GHL Support forum but thought I may get a wider response from KHD users here).

I have been using the KHD to adjust Carbonate dosing for about a month now. First I used the adaptive mode and then switched to the add-on control mode about two weeks ago. By the way, I love this machine! ;Joyful

Normal carbonate dosing is set at 4ml 24x per day (96ml daily total).

When I had the adaptive mode I set it at a volume change of 100% and a max and min dosing limit at 50% with 4 tests a day.

I was getting daily variations of from 0.4 to 0.7KH.

So I decided to try the add-on control since I know how many ml of my carbonate solution are needed to raise the KH by 1 in my tank: 60ml.

First I set the volume change at 12ml and a max of 3 and a min of 3. Still pretty large daily variations.

Now I am trying the following:

- Increasing testing from four to six times a day.
- Kept the volume change at 12ml but the max is now 8ml and min is 4ml. The min basically stops dosing my carbonate solution.

My thinking is that the combination of the increased testing frequency and the larger corrections will reduce the daily variations.

So my questions:

1. Do my settings make sense?
2. What are others experiences in terms of daily KH variations when using the KH control feature (and what are your settings)?
3. Which control method minimizes variations the most: add-on or adaptive?

Inputs appreciated!:)

Thanks,

Laith
 
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Lasse

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Sorry - no experiences with the KH director and controlling - only use it as a monitoring equipment at work. But I have heard other reports about swinging KH levels during the day with steady dosing of alk. But if it is a bad thing - I do not know.

Sincerely Lasse
 

Mortie31

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I only use mine for monitoring I measure 6 times a day and I get a daily swing of 0.2 dkh max, alk consumption of SPS corals in particular varies during a 24 hr period, and I found this way to be more stable than allowing the director to make constant small adjustments.. I feel the constant adjustment of automated dosing allows overshooting of the setpoint so you end up with a yoyoing effect, be interesting to see what others input.
 
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WWIII

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I've found the best way to keep the alk stable is to use the adaptive mode with settings at 50% 100% 100%. Then adjust your actual doser by a 1/2 ml per dose. So if you're dosing 4 ml per dose 24x per day and it can't quite keep up then change the dose to 4.5ml. The settings on the kh director are very safe when we are only dosing a few ml at a time, testing multiple times per day.

The consumption in the tank will change, but keep adjusting the dosers by +/- .5ml per dose. When I have it set up this way I have never seen more than a .3 dkh change. 90% of the time it stays within .1 dkh.
 

Ditto

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Sorry was in travel mode so could only tag people :)

I have found the 6 test a day has helped keep it stable.

I also am doing the same setttings as @WWIII and been within .1.

It had fluctuated more but it was because I was consuming more and just increased by
.5 until it came back into check.
 
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Laith

Laith

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Intuitively I was also thinking that the adaptive mode would be the most stable as it works with percentage increases/decreases instead of absolute ml values. Almost like it has a learning capacity :p.

I have also noticed that in the add-on mode it sometimes shows no correction applied when the KH value is only 0.1 off the nominal value (both above and below). I think that in the adaptive mode it was always showing a percentage increase or decrease whenever it was off of the nominal value, even by 0.1.

Anyway, my change to six measurements a day and larger corrections seem to have reduced the daily variations. But I'll leave it like that for a couple of days to see. Then I may move it back to adaptive mode and try at 50%, 100%, 100%.

And I agree with adjusting the base dosage. It would be nice if the KHD actually logged the corrections it was making. I've looked everywhere for that data but can't find it? ;Bookworm

Thanks for the inputs. I think the more info we get from people using the KHD the more we'll understand what seems to work the best at keeping KH stability using this device, which is the whole point of a KH controller in the first place (unless you are just using it for monitoring of course)...
 
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Laith

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So, adaptive mode at 50%,100%,100% with my current dosing would be equal to 2ml, 4ml, 4ml dosing adjustments as my base dose is 4ml 24x a day. Have I understood correctly?

Currently with the add-on dosing I'm at 12ml, 8ml, 4ml.

These are the details that can be confusing... so it is better to have a lower change for the 1KH adjustment figure but then double the maximum and minimum amounts for the adjustments? :confused:
 
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Laith

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Update:

For several days after implementing the 6x per day testing and setting the add-on mode to 12ml, 8ml and 4ml, the variation in KH narrowed down to 0.2KH so I thought this was a setting that seemed to work well.

The KHD is set to measure every four hours starting at noon. My light period is noon to midnight with a five hour peak in the middle. The KHD is set for a nominal KH of 8. So with the new setting my KH was swinging from 7.9 to 8.1.

Then last night's measurements: 8pm: 7.8 KH, midnight: 7.6 KH, 4am: 7.6 KH, 8am: 8.8 KH (!)

The only adjustment amount that I can confirm is that this morning at 7am it was showing an adjustment of 5ml so I assume it was making the same adjustment as of midnight. Therefore probably eight adjustments of 5ml between midnight and 8am, or 40ml on top of the base dose. 40ml is equivalent to about 0.67 KH. This combined with a lower uptake of KH after lights out at midnight seems to be what drove the KH to 8.8.

So as @WWIII and @Ditto suggested, I have changed the control mode to adaptive using the 50%, 100%, 100% settings. The problem with my previous settings is that when an adjustment is necessary it becomes excessive and you get that yoyo effect that @Mortie31 referred to.

Question: Does the KHD log adjustments? and if so, where can one find that log? in the above scenario and for anyone dialling in the unit, wouldn't a log of adjustments be good to have? (@[email protected] ?)
 
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Mortie31

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Update:

For several days after implementing the 6x per day testing and setting the add-on mode to 12ml, 8ml and 4ml, the variation in KH narrowed down to 0.2KH so I thought this was a setting that seemed to work well.

The KHD is set to measure every four hours starting at noon. My light period is noon to midnight with a five hour peak in the middle. The KHD is set for a nominal KH of 8. So with the new setting my KH was swinging from 7.9 to 8.1.

Then last night's measurements: 8pm: 7.8 KH, midnight: 7.6 KH, 4am: 7.6 KH, 8am: 8.8 KH (!)

The only adjustment amount that I can confirm is that this morning at 7am it was showing an adjustment of 5ml so I assume it was making the same adjustment as of midnight. Therefore probably eight adjustments of 5ml between midnight and 8am, or 40ml on top of the base dose. 40ml is equivalent to about 0.67 KH. This combined with a lower uptake of KH after lights out at midnight seems to be what drove the KH to 8.8.

So as @WWIII and @Ditto suggested, I have changed the control mode to adaptive using the 50%, 100%, 100% settings. The problem with my previous settings is that when an adjustment is necessary it becomes excessive and you get that yoyo effect that @Mortie31 referred to.

Question: Does the DKH log adjustments? and if so, where can one find that log? in the above scenario and for anyone dialling in the unit, wouldn't a log of adjustments be good to have?
I don’t think there is a log, if there is I can’t find it. Unfortunately you are seeing the same problems I had, maybe something to try is to use adaptive and use smaller adjustments ie 20% to 40% and increase the frequency of measuring, so you get a more accurate base dosing level, therefore limiting changes in dosing volume and allowing faster correction of measurements. I couldn’t do 12 or 24 measurements a day as I would of liked due to my salinity falling, this is why I still manually adjust mine as these swings seem to get bigger as average Alk dosing increases..
 

Ditto

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Good Morning,

There are no logs, but been told they are working it that.

Your dosing scheduled is 4ml 24 times a day.

And your testing every 4 hours starting at 6am

Make sure you are dosing is between the hours and not in the same hour of the test.

I dose 24 times start at 12:15 12:30 which is my alkalinity and 12:45 is my part 3.

With my test also starting at 6am every 6 hours.

I am thinking Reduce your dosing schedule to 3ml maybe even 2ml 24 hours a day @WWIII what do you think? This would allow the adjustment to take place without the large swing.

Once you do this we need to pay attention to the dosage % that going to tell us the % of the additional dosage amount.


20994647-139A-47AE-AB8A-C4E7052A56C1.png

This was this morning 6 am test and it 0% calculated percentage adjustment needed.

I am also going to tag
@[email protected] and @[email protected] @Matthias Gross to see what they think also.
 
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Laith

Laith

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I am testing 6x a day or every four hours, starting at midnight. And the carbonate dosing is set to dose at 30 minutes past the hour so the test and the dose are not happening together.

And reducing the hourly dosing amount may be an idea... especially to get my KH level back down a bit faster. But I don't think it's a long term solution as the drop from a KH of 8 (noon yesterday) to a KH of 7.6 at midnight last night shows to me that 4ml a dose is not enough to keep up with consumption?

For info the latest test which took place at noon (my time ;), or almost an hour ago) still showed a KH of 8.8, despite an adjustment of -40% the last four doses. Now it is showing an adjustment of -42%...
 

Ditto

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I would reduce the dosage down to at least 2 to allow it to come down gradually. Your still dosing approx 2.3ml even at the -40%.

At 50% volume change

at 8.0 it going to dose the doser set amount.

at 7.5 it going to dose 25% more

at 7.0 it going to dose 50% more


So it should be working as such with a Nominal value of 8.0 and 50% Volume Change

At 9.0 dosed reduced to 2 ml

At 8.5 dose reduced to 3 ml

At 8.0 no change remains at 4ml

At 7.5 dose Increased to 5 ml

At 7.0 dose increased to 6 ml


I still believe it needs to be reduced it to 3ml 24x a day @WWIII - What do you think? It needs room to be able to adjust but not overdose.

At 9.0 dosed reduced to 1.5 ml

At 8.5 dose reduced to 2.25 ml

At 8.0 no change remains at 3 ml

At 7.5 dose Increased to 3.75 ml

At 7.0 dose increased to 4.5 ml
 
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Laith

Laith

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So if I understand you correctly, I should lower the base dose to 2ml per dose in order to bring the KH down more rapidly towards the nominal value.

Then once there, I should set the base dose at 3ml per dose.

And keep the 50%, 100%, 100% settings.

Then, as per the original suggestions, to increase/decrease this by 0.5ml increments until the base dose is dialed in?
 

Ditto

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I believe yes, we need room for the compensation to take place and not overdose, which is what we are trying to avoid. But first we need to get you back down to around 8 :)

I have set one my tanks to test every 4 hours now also from the 6. So we can both watch what our tanks are doing.
 

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I agree with the plan you all have laid out above. I'm not sure why the spikes are happening really? Other than the alk is just building up in between tests. Once you get the alk back down to 8 and try the 3ml with 50/50/100%, if "it" starts to do the same thing you may want to increase testing frequency to 12x per day for a few days to a week. The tanks alkalinity consumption needs will change over time, but not that rapidly. Need to really nail down what the dosage is that is truly needed.

One other thought. Are you using gfo in your system? If you are, gfo when new will lower the alkalinity in a tank fairly drastically (especially high capacity gfo). Then when it's a few days old, it has little effect on alkalinity. Well that causes a problem when we are automating dosing based on testing. If we adjust the dosing because the gfo has lowered the alkalinity, well then once that effect is gone, we are overdosing the tank. I've seen it and confirmed it several times. It's actually a pretty significant effect.
 
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