Sudden increase in Alkalinity

[KingBlingTX]

I'm scratching my head today because I had a sudden jump in my ALK. For the last couple of weeks, I've been dosing Aquaforest Components 1+, 2+, & 3+ at a level of 14 ml/day (which translates to a little less than 0.2 dKh consumption per day in my ~45 gallons of water.) I measure ALK about the same time every day and it has consistently been at 7.6 dKh. Today it jumped to 8.6. I re-tested this 3 separate times as I didn't believe it. What could have happened?

My NO3 and PO4 have been essentially 0 for the last couple of weeks (which i am trying to increase some.) This makes me worried about tips burning on the SPS with the higher ALK.

I checked the dosing pump to see if it is still in calibration and dosing the correct amount. It is. I have turned it off for now until I see what happens with the ALK over the next couple of days.

 

[WDKegge]

Been scratching my head on this one as well, normally I stay consistent at 8DKH with dosing, a recent test showed it at 9.3. As growth on my sps went up in my tank I was having to adjust to RAISE the amount dosed per day, but the increase tells me that growth has slowed down and corals are no long using as much alk. I am still trying to track down what might be the cause of the slowed growth in my tank, but I would look to other things in your tank as well.

 

[KingBlingTX]

Been scratching my head on this one as well, normally I stay consistent at 8DKH with dosing, a recent test showed it at 9.3. As growth on my sps went up in my tank I was having to adjust to RAISE the amount dosed per day, but the increase tells me that growth has slowed down and corals are no long using as much alk. I am still trying to track down what might be the cause of the slowed growth in my tank, but I would look to other things in your tank as well.

Like you, my first thought was perhaps growth/consumption stalled. However, since my tank was consistently consuming 0.2 dKH/day, if it stopped altogether it should only rise 0.2 dKH not a full 1 dKH.

 

[Randy Holmes-Farley Verified Community Expert]

Could be many things, including testing error (despite the repeats), a change in calcification rates (due to changed pH, or other factors), and dosing issues.

 

[Downbeach]

Are you using any type of pH buffer? If so, that will add to your alk.

 

[KingBlingTX]

Are you using any type of pH buffer? If so, that will add to your alk.

I don't use any pH buffer. My pH has been cycling between 7.95-8.20 (per Apex probe) daily, without any noticeable change. I'm leaning towards something wrong happened with the dosing, although I checked it to confirm calibration was still correct. I did notice some air bubbles in the line near the dosing pump for ALK, so I cleared those out. Maybe that had something to do with it.