KHD does NOT correct my alkalinity

[Adri-DSR]

Hi,

I have the KHD installed now for 4 days. It measure my alkalinity at 7.5. I have the nominal value set at 8.
I am using the ADD-on setting:

Volume change: 3
Limit for KH Raise: 5
Limit for KH lower: 5
Calculated adjustment: 1

Pump 4 is used to dose the KH solution 24 times a day.
My KH solution strength is 33.3 ml / 100 liter to raise 1 dKh.
Correction strength is 16.6 ml / 100 liter

My tank contains 334 liter. So to raise my Alkalinity from 7.5 to 8 the KHD needs to dose 27.82 ml extra. The calculated adjustment is 1 ml. So after 1 day my Alkalinity should be at 8.

Why is my Alkalinity still on 7.5. It already should be at 8 now after 4 days?

[arking_mark]

I think your volume change is off. For a 1 dKH deviation, you need ~100ml of your supplement. You have this set to 3ml so a .5 deviation will add 1.5ml of supplement for your next dose.

With your current setting, you will be adding roughly ~36ml for the day which is less the the nominal .5dkh you would minimally use.

[Adri-DSR]

I think your volume change is off. For a 1 dKH deviation, you need ~100ml of your supplement. You have this set to 3ml so a .5 deviation will add 1.5ml of supplement for your next dose.

With your current setting, you will be adding roughly ~36ml for the day which is less the the nominal .5dkh you would minimally use.

Mark, i dose 132 ml a day devided in 24 doses, that is 5.5 ml per dosing. That will keep my alkalinity almost at level. The KHD should take care of the rest.

To raise 1 dKH I need only 57 ml of my solution. I made a mistake with the strength.
My tank uses 2.39 dKH per day, that is where the 132 ml per day is for.

[arking_mark]

What is your 1dKH deviation setting?

[Adri-DSR]

Which setting is that?

[arking_mark]

Screenshot_20200929-184027_GHL Connect.jpg

[Adri-DSR]

The KHD shows me that it corrects the dosings with 1 ml, see screendump.

I dose 24 times a day, 24 x 1 ml extra. This is almost the complete correction to go from 7.5 to 8

Unless this 1 ml is divided by 24 dosings, then it make sense why it is still on 7.5

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[arking_mark]

Here's how I set it up and why...

1. I set doser for the nominal dose a reef tank uses per day, which is .5dKH. For my tank, I dose 6 times a day and require 24ml of supplement. So 4ml per dose. This ensures that if my tank is at target 8dKH, it still will dose this minimum amout that will be used up b4 next dose.
2. I set the 1dKH deviation volume to the actual ml needed to raise my dKH by 1. The KHD is set to measure 30 minutes b4 dosing. This ensures that after every measurement, my dKH is replenished to at least 8 plus my minimal dose.
3. I limit the max/min dose adjustment to .25dKH because I never want a larger change then that. It protects my tank from anomalous readings as well.

With these setting, I'm typically between 7.9 and 8.1 dKH. Sometimes a little higher and sometimes a little lower. The dKH consumption of my tank varries throughout the day. The more measurements / doses you do the tighter you can lock in the target dKH.

[Adri-DSR]

I think you are right. I have increased the settings and seen that the KHD also corrected the dosage. Guess I have to fine tune it now.

Thank you Mark for your advice and patience.

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