Alkalinity Consumption Significantly Increasing While on Vacation…What Gives?

[george9]

Hi all,
Curious to see if anyone has any ideas as to why my alkalinity consumption skyrockets each time I go on vacation lol. This has happened two times now, each with 4-5 day trips where I pre-measure everything I regularly dose and instruct a friend to dose the tank for me while I am away.
I just arrived back from a 4ish day trip (left on Thursday 5/25 and arrived back early Tuesday morning 5/30. I maintain alk in my 32g biocube using AFR around 4 ml daily to keep me at 8.0-8.2 dkh. I measured small containers of AFR, AB+, and phyto before I left so a friend can easily dose the tank each day with the “perfect” amount that has been holding things stable for months. I left the tank at 8.2dkh. I arrived home this morning and checked the alk right away to see it is at 6.5 dkh! How is it that 4ml of AFR maintains my alk at 8.0 when I am around (and has been for months) but suddenly does not keep things stable when I am away?
We have to assume my friend was dosing correctly, and I trust her 100% to be doing what she was saying she was doing, so what can biologically or chemically cause a sudden increase like this?
Is it simply from not tinkering with the tank on a daily basis? Typically I will stick my hand in at least one time a day to either feed or empty my skimmer cup but don’t think I particularly am too annoying to my tank on a daily basis.

This also happened on another trip I took where I came home to alk about 1dkh too low despite regular dosing so it is not an isolated incident.

Corals look good for now although I haven’t seen any of them in daylight yet since it is the middle of the night. SPS especially has extreme polyp extension and no necrosis but my Acans are a bit more deflated than usual at night and there is pretty obvious bleaching on a psamocora which is a bummer. That seems to be the only evident result of this drop. It probably wasn’t a sudden alk drop but more of a gradual drop over the 5 days.

How quickly should I plan on raising my alk back up? I don’t want to kill my acros by swinging the alk from low back to normal too fast. I plan on doing around .2-.3dkh each day, but am interested to hear any thoughts about this.

Thanks in advance!

 

[GMF21]

My guess…with no one there then less CO2 in the room so the Ph rose. The result is faster coral growth, and with it, higher alk consumption.

 

[george9]

My guess…with no one there then less CO2 in the room so the Ph rose. The result is faster coral growth, and with it, higher alk consumption.

Ah genius, I did not think of this! I do struggle with ph on the lower end (7.8-8.0) with 2 people and 2 dogs in a 1 bedroom apartment. Since I am quickly running out of room in the Biocube I didn’t really want a Co2 scrubber because growth is decent enough

 

[homer1475]

My guess…with no one there then less CO2 in the room so the Ph rose. The result is faster coral growth, and with it, higher alk consumption.

Yup this is exactly what I was thinking too.

No one home to create massive amounts of co2, No co2 buildup, so your PH rose, Higher PH causes corals to consume more elements, and grow faster.

 

[Randy Holmes-Farley]

Abiotic precipitation also increases as pH rises, so both effects will increase when folks are not home.

 

[Propane]

I’m gonna ask a newbie question. Would those parameters rise on their own since the owner is back home and the co2 would be back.

 

[GARRIGA]

Curious if the pH actually did go Up when people were gone for a short period. Was that checked because I don’t see that quick of a response and my house has that same issue. Too many people and pets.

 

[Randy Holmes-Farley]

I’m gonna ask a newbie question. Would those parameters rise on their own since the owner is back home and the co2 would be back.

Assuming there is automated dosing, yes. Without dosing, generally not.

 

[george9]

Curious if the pH actually did go
Up when people were gone for a short period. Was that checked because I don’t see that quick of a response and my house has that same issue. Too many people and pets.

Unfortunately I don’t monitor pH continuously to know what exactly happened to it when I left. The acros were noticeably larger though, so I don’t doubt it happened. I am thinking of buying a ph monitor now just because I really am so curious. My alk has never been used up that quick, I was shocked to see it that low with my usual dosing. It seems the usage nearly doubled in that short time