Alkalinity/Calcium Stability - What You Definition of True Stability?

[Fenwickwick]

Everyone knows one of the keys to successful coral growth is stable Alk/Ca. My question is, what is the real definition of stable? Are we talking about a rock solid unwavering alk of 9.5? or is bouncing around from 9 to 9.5 back to 9.2 , etc. ok?

Here's my trident results from the last few days. I dose several times a day, but find it hard to get much better than this.

For reference, everything is growing and happy in my tank, SPS and LPS alike. I'd just like to know everyone's thoughts!

 

[arking_mark]

The obvious answer is unwavering Alk/Ca.

However, our tanks aren't oceans.

So the better question is what are acceptable swings.

For Ca, which is very abundant in seawater and our tanks, I'm not sure it matters. As long as the Ca is abundant, you're good. Say 350ppm or higher.

For Alk, it's a different story. Its not that abundant and a tank typically consumes anywhere from 0.5 to 5.5dKH a day and is highly dependent on tank maturity and stocking.

Based on experienced hobbiest, the normally recommended swings are less than 1dKH per day and no more than 0.5dKH change at a single adjustment.

 

[SPS2020]

I agree with @arking_mark and also remember that alk swings will also affect the pH and keep that to no more than .2 at a single adjustment.