2 part dosing alk, calc, and magn interaction.

[thoeffe]

So I have been trying to get my alk level up to 8.0 its currently at 7.7. My magnesium is at 1260 and my calcium is around 410. I have been dosing 1/4tsp(.25) of sodium carbonate(baked baking soda) every day and it doesn't seem to want to go above 7.7 yet the reef chemical calculator says to add that much to raise alk to 8.0. So my question is 1. Is their a way that I can know if its being used by the corals or if its just precipitating? 2. How exactly do the three (alk, calc, magn) affect each other. Like I get that if magnesium is low that its difficult to keep calcium and alkalinity up. But is it like steps, so lets say magnesium is at 1260 and it will allow me to have a max of 7.7 alk and if I raise it to 1280 I could have a max of 8.0. I guess I'm just trying to figure out how each one affects the other two when it is too high or too low. 3. Should I just bump the dose up to 1/2 tsp(2.7grams) per day? Should I be dosing calcium as well even though its at what i've read is an acceptable level?

 

[Randy Holmes-Farley Verified Community Expert]

There’s no way to know whether the alk is precipitating (some usually does) is mostly being used by corals. There’s no direct limiting value to alk that directly depends on magnesium or anything else. High pH drives precipitation more than other factors, typically.

Just add more if you want alk higher, and see what happens.

 

[Randy Holmes-Farley Verified Community Expert]

I would dose them all at the recommended ratio to each other based on the need for alk, unless calcium is already too high.

 

[thoeffe]

I would dose them all at the recommended ratio to each other based on the need for alk, unless calcium is already too high.

I read in another post by you that said "Adding 0.5 meq/L (1.4 dKH) sodium carbonate causes about a 0.35 pH unit boost in pH" The reef calculator says that I should not dose more than affects the pH by 0.20. So is it safe to say that I can add up to .8dkh at a time or will that still affect my coral? I am just worried about overshooting than bringing it back down and always fiddling with it and never getting it stable.

 

[Randy Holmes-Farley Verified Community Expert]

There’s no reason to not spread it out over several doses.

 

[Ryan Wolf]

There’s no way to know whether the alk is precipitating (some usually does) is mostly being used by corals. There’s no direct limiting value to alk that directly depends on magnesium or anything else. High pH drives precipitation more than other factors, typically.

Just add more if you want alk higher, and see what happens.

2 PART DOSING Q: Could my mag at 1440 be impacting the impact of 2 part? Using B-Ionic on my 200 gallon mixed reef. I stopped dosing mag months ago when it shot up to 1600. It’s since gone down. I deplete about 1.5dkh daily. I’m currently dosing 70ml each of alk and ca on opposite 12 hour schedules. Ca is 500. Dkh is 6.7-7.0. Do I just up the 2 part dosing components and ignore mag number. Or stop all 2 part until mag gets into 1350 range and then pick up??? Any suggestions?