Water chemistry question

[asylumdown]

I'm hoping someone with a background in chemistry can help me out with this, as I'm not sure if this is normal.

I use an auto-doser to keep my calcium and alkalinity levels where they're supposed to be. The weird thing is that I'm finding I need to dispense nearly double the amount of alkalinity solution every day than calcium to keep levels where they're supposed to be.

For example, if I make a solution using a product like turbo calcium, or even straight up calcium chloride with one cup per gallon of water, and I make another solution of one cup of baking soda per gallon of water, I'll need to dose almost exactly double the amount of baking soda to keep my dKH at acceptable levels compared to calcium

I thought that corals used calcium and carbonate in equivalent proportions? Is there something else going on that I'm not aware of? Or does this have to do with the native concentrations of 1 cup of baking soda vs 1 cup of calcium chloride?

Also, I recently switched to baking my baking soda so I was dosing carbonate instead of bicarbonate. I didn't realize that the dosing pump hosing for the carbonate had gotten blocked, and I had just doubled the concentration of my calcium solution in the current batch of solution to try and cut back on the number of times I need to make fresh solution. I didn't pay attention for a few days and when I tested, my alk was way down around 6.5 and my calcium was sky high at 485. When I fixed the tubing and started increasing my dKH, half of my pumps failed because of spontaneous precipitation (thank god for vinegar..)

Was this a) because the increase in alkalinity pushed the already super high calcium out of solution or b) because I was using carbonate, which apparently precipitates out of solution easier? (My magnesium levels were a little low at 1150 at the time).

Any insight would be greatly appreciated. I'm no chemist and I'm having a hard time wading through the online materials.

[lastlight]

I'm by no means a chemist but it certainly depends how saturated each solution is that you're dosing. I know that if I follow the BRS instructions for my chems...I should be dosing pretty close to the same of each. I'm not sure if your mixes are equal 'strength' or not. Also, for the longest time I was dosing quite a bit more alk than calcium (still do but they're getting closer together) as the salt I use has elevated calcium levels but target alk levels.

Hope that helps some.

[mark]

not sure either but what I got from Randy Holmes-Farley was when using his recipe is the CA and Alk are added in even amounts. Are you adding the Mg part to balance things out?

[asylumdown]

yep, definitely adding the mg. I'm not dosing it currently, but adding it by hand when needed. currently at 1300.