KHD Testing Frequency and Sample Size

[eliasi]

Hi all.

how often are people allowing their KHD to test every day? I have mine set to 4 times per day but I'm starting to think this is a little overkill. Also, what water sample size do people set? GHL recommend 100ml for accuracy, mine is set to 80ml, but I read that some are getting stable results with 60ml. Obviously the bigger the sample size, the more reagent is going to be used per test.

Just trying to ***** consumption of reagent and whether it's worth the extra testing frequency and sample size to justify the use of more reagent.

Tanks and sorry if this is a dumb question.

 

[AZMSGT]

4 x 80 on mine

 

[griff500]

It's not a dumb question at all - quite an interesting one in my opinion.

I am testing eight times per day and dosing after each test. The level seems fairly controlled at this frequency of testing and better than it was with less frequent testing, although an updated algorithm to take into account lower consumption rates at night would be handy.

 

[Kyl]

4x 80ml, dkh around 7.8 - 8. I've gone through 1.5L of reagent since starting with my KHD, I believe it was around mid August 2019. At the start to dial things in I was running 8x a day for a number of weeks. Higher dKH will use more reagent per test.

 

[Ditto]

First tank 6 times 100 ml each one tank. DKH is 7.5 (Drifts between 7.4 and 7.6)
Second tank 2 times at 100 ml each DKH 7.5 (Drifts between 7.3 and 7.7) (QT tank)

 

[chema]

2 x 100 ml per day. KH solid at 7,7

 

[vangvace]

Currently 4x80 as I am dialing in my calcium reactor. Planning on dropping to 3x80.

 

[DrSamwise]

I have been testing a lot of lower amounts of both samplings as well as sample size, smallest stable I can get is 3x60ml, it keeps KH 8.2-8.5, but that requires that there are no big drastic changes like large water changes etc... However, in all testing schemes the largest problem is the nightime, consumption drops then and almost always highest KH is in the morning.

There are no other solutions to this than either measure more samples per 24h or I have also tried to adjust dosing so that I set dosing times and amounts manually and so that dosing in night time is less than day time, but still let KHD adjust those manually set dosing amounts. It works but takes some time to program and some time modify.

However, best solution I ended up running is this 3x60ml so that first sampling is 9am, second 5pm and last 1am. And I dose every hour. It still suffers slightly from nightime consumption drop but it is relatively ok. Waiting also for GHL to update algorithm to take nightime in account.

 

[sylvius]

Sorry to respond to an old thread but my KHD is on the way and I am working on having things ready for it. For decreased nighttime consumption, couldn't you achieve that by having two virtual dosing pumps, one that is scheduled during the day and has a larger baseline dose and the other running at night with a smaller baseline dose and both with control by KH then tie them together with an OR and set your real dosing pump to a switch tied to the PL gate? If using two part, you could have a second PL gate set as delayed on from the first one so part B of two part would automatically go in some set time after part one. Would that work?

 

[Member No 1]

I test 6 times per day, I use 2 part, have the 2 dosing heads set to Adaptive Control and Automatic Dose with the doses per day set to 100 and the rate is 0.9ml/dose. Starting time for Part A is 12:00am Part B 12:05am.
My dKh stays steady at 8.9-9.1 for the entire day. I don't see any increase or decease during the day/night.
Calcium level is steady at 440-460ppm.
KISS - Keep It Simple. Don't over think it.

 

[sylvius]

Perfect, thanks!