Variable Alk uptake - is this normal?

[carri10]

Hiya all.
I consistently dose 70ml / day of Randy’s three part (Ca and Alk, I also dose the relevant Mg). I do this more or less regardless of my alk readings, I.e not changing dose in reaction to readings (unless something gets well out of wack)
I do not use my GHL KH director to control Alk ( I don’t trust it that much).

Anyway, my alk levels vary throughout the week, even though they stay around a mean.

I am wondering if this level of variation is

normal?

Thanks.
I include three photos
1) a representative alk trace
2) a representative pH trace
3) a representative conductivity trace.

Please note, I am fairly sure this is not variation due to measurement error.
alk is always measured at 08:00 and 20:00 and I have performed triplicate measurements a few times, with the three results always coming out within 0.1dKH of each other.
KH director gets calibrated every 6 weeks.

Any opinions welcome

 

[carri10]

Sorry. Screwed up inserting the screen shots! First shot is conductivity - the one right in the middle of the text! Alk is the one just at the end of main text.

 

[Randy Holmes-Farley Verified Community Expert]

How are you dosing? Most of the graph looks pretty stable with a once a day spike?

 

[carri10]

7 doses of 10ml spaced evenly through a 24 hour day.
For example, from 21st Jan to 27th, under a constant dosing regime, alk goes from 10 to 9.25. And then drifts back up again, again, with constant dosing.

If this is normal, that’s fine, I’ll stop worrying.
Often difficult to not what to worry about and what not too.

 

[Randy Holmes-Farley Verified Community Expert]

From Jan 27 to Feb 10, it looks like stable demand to me.

If you dosed just during the light cycle, you might squeeze down the daily alk change since that is likely when most demand is.

 

[carri10]

Cool. Thanks. Will change dose to be mainly in light cycle.

By the way, appreciate the help and DIY recipes you freely distribute. It has saved a lot of people and lot of time, mistakes and money.