This doesn't make any sense to me -

[reeferJ]

A couple of weeks ago, my readings were:

pH: 8.2
Alk: 16+
CA: 360

I shut off my calcium reactor until my Alk got down to 10.4, during that time I was dosing Turbo Calcium, and got my CA up to 400. At that time my pH was still 8.2. Last week I turned my reactor back on and now my readings are:

pH: 8.0
Alk: 15.2
CA: 400

How could my Alk rise and my pH lower?
Help!

 

[jdeets]

The pH is lower because when you're using the reactor, you have more CO2 in the water. You can have high alk and low pH if there is lots of CO2 in solution. That's the easy part.

What seems strange to me is that when you turned the reactor back on, your alk increased but your Ca stayed the same. According to the chemical relationship between Ca and alk, if your alk increased 5 dKH using balanced supplementation, then your Ca should have increased 50 ppm, roughly.

Did you do any water changes in connection with the calcium chloride supplementation? What is your Mg level? CaCl2 will cause an ionic imbalance over time, leaving excess Cl- ions in solution. Lower Ca and higher alk could be related to an imbalance. It's important when using CaCl2 to do water changes to minimize the effect of the ionic imbalance that necessarily results from its use.

Sorry I don't have a better explanation. Your numbers really do seem strange to me. These are the only possibilities I can come up with at the moment.

Also, before you do anything, run your tests again to confirm.

 

[reeferJ]

I didn't do any water changes while adding the Turbo Calcium (didn't know better) I don't know the Mg level (no test kit) Is there anything I can do to raise the pH without raising the Alk?

 

[jdeets]

Generally, any buffer will raise alk but will only temporarily raise pH. Kalk would be the best possibility, as it will increase pH and it is balanced--so that any increase in alk will correspond to an increase in Ca.

Before I upgraded to my 180 I had terrible trouble keeping my pH elevated, and especially so when I started using a Ca rxr. I dripped kalk at night and sometimes 24/7 to keep my pH up.

Before you do anything, perform a simple test to see if excess dissolved CO2 is your problem. Take a container of tank water and test the pH. Then, add an airstone and aerate for an hour or two. Test the pH again. If it's come up, then your problem is excess CO2.

The best remedy, besides the kalk, would be to increase gas exchange in your system. More surface turbulence, a good skimmer, macroalgae, etc. In my case, I went from having no overflows and a really crappy built-in skimmer to having overflows, refugium with macro, more intense lighting, and a much better skimmer. I haven't had any pH problems with the new system, even with the Ca rxr running at a higher rate than it ever has.

HTH