Dropping ALK

LittleMaui · Jan 6, 2017

I'm curious why my alkalinity has been dropping recently, but PH staying steady. I use kalkwasser to maintain calcium and alkalinity. My PH has been staying around 8.3, calcium around 420 and magnesium around 1350. But, my alkalinity drops steadily each day. Today it was at 6.3. I've been increasing it using baking soda. Any ideas?

Shawn

Elementalj · Jan 6, 2017

shaywood said:
I'm curious why my alkalinity has been dropping recently, but PH staying steady. I use kalkwasser to maintain calcium and alkalinity. My PH has been staying around 8.3, calcium around 420 and magnesium around 1350. But, my alkalinity drops steadily each day. Today it was at 6.3. I've been increasing it using baking soda. Any ideas?

Shawn

Consumption?

LittleMaui · Jan 6, 2017

Consumption? Are you saying it's normal for alkalinity to drop 1 dkh daily without a corresponding impact on PH?

Elementalj · Jan 6, 2017

I can say it's happened to me! You're adding kalk, and it only provides temporary alkalinity. Increasing it with baking soda is fine. What corals are you currently keeping in the system?

LittleMaui · Jan 6, 2017

Mostly SPS, some LPS. I added zeovit system about 5 weeks ago. I'm curious if that might impact ALK. I'm not use to ALK dropping, but PH staying high. I use a CO2 scrubber to also increase PH, along with Kalkwasser.

Elementalj · Jan 6, 2017

I think with a combination of everything you got going there it'll keep the pH boosted but it will still allow alkalinity to drop. Is there a way for you to dial back the input for the CO2 scrubber?

Elementalj · Jan 6, 2017

Hang on, let me get @Rick.45cal in here. He's running zeovit I believe.

Rick.45cal · Jan 6, 2017

Alkalinity doesn't exactly correlate directly with pH. It's just a measure of carbonate ions in the water. Your alkalinity is being consumed by your tank inhabitants. 1dKH a day is pretty normal I think. I'm not 100% positive what effects CaOH has on your alkalinity. @Randy Holmes-Farley is probably the guy you wanna ask. :)

My guess is that you need to increase your baking soda additions to make up for the increased consumption of alkalinity. I personally dose 2 part and find it much more friendly than kalkwasser. Though I have used it in the past too.

Your high pH is a product of low dissolved CO2 in the water and or Kalkwasser dosing. You can't really judge your alkalinity based on pH. Only good way to tell consumption trends are to test the same time every 24 hours.