Carbon Dosing and PH (and other params)

[shornik]

OK I've started dosing carbon (vodka) and I'm at the beginning of week 4. I have noticed my high nitrates :squigglemouth: trending down :bigsmile: but not quite where I want them to be yet. I have also noticed (starting about 1 week ago) that my PH seems to also be lowering (its about 7.8 now, though honestly I hate API for figuring this out, what's the best way to test PH?). While at the same time things like my Calcium and Magnesium are increasing (again I started noticing this 1 week ago, I use Red Sea titration for these tests). I haven't changed anything other than the carbon, still do weekly water changes (average 8% each week). My feeding (or overfeeding) hasn't changed either. I've introduced a few new corals over this 4 week time so if anything I'd think if my Calcium /Mag would be changing in would be going down not up.

So is there any reason that the carbon dosing is contributing to these other changes PH (decreasing) Calcium/Mag (increasing)? Or is is just one of the joys of this hobby?

Thanks in advance for your answers.

 

[Randy Holmes-Farley Verified Community Expert]

pH is best measured with a pH meter which can be calibrated. This has more:

Aquarium Chemistry: Measuring pH with a Meter ? Advanced Aquarist | Aquarist Magazine and Blog

Organic carbon dosing, regardless of the type used, will tend to reduce pH as the organic ends up as carbon dioxide after being metabolized.

The calcium and magnesium changes are unrelated. How much did it change?

 

[shornik]

Thanks Randy and amazingly the carbon to carbon dioxide reducing PH makes sense. Like I tell my kids all the time, reading makes you smart
I'll read up on the PH meter article and definitely get something other than the API I've been using.
As far as the other changes the Calcium went from 430 to ~450 over the last few weeks (my salt mix says it targets 415). My Magnesium went from 1300 - 1380 over the same time period. Neither are terrible (I don't think) but just seems weird that they are increasing and the only thing that I'm doing differently is the dosing.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks Randy and amazingly the carbon to carbon dioxide reducing PH makes sense. Like I tell my kids all the time, reading makes you smart
I'll read up on the PH meter article and definitely get something other than the API I've been using.
As far as the other changes the Calcium went from 430 to ~450 over the last few weeks (my salt mix says it targets 415). My Magnesium went from 1300 - 1380 over the same time period. Neither are terrible (I don't think) but just seems weird that they are increasing and the only thing that I'm doing differently is the dosing.

Could just be testing error, or drift in the composition of the salt mix used for water changes. Definitely not a change in demand in magnesium to cause a boost like that, since the actual demand is quite low.