New tank chewing through alk...but not anything else

[jlbrew3]

Hi everyone,

I have a Reefer 425 that's been cycling for ~3 months at this point. Lights have been off (with the exception of the moonlight mode on the Radions that I can't seem to disable) during this time. I added a jar of pods from AlgaeBarn and some live reef rubble from AquaBiomics to the sump a couple weeks ago but other than that there's no livestock whatsoever in the tank.

Before I added those, my alk was rock steady, exactly as I would expect given an empty tank. But basically as soon as I added those it's been chewing through alk. I ignored it for a while and it just kept falling steadily from the 8s into the 5s. Maybe 0.1dkh/day on average. But, since I intend to add my first fish tomorrow, I thought I'd try to get it back up to the level where I intend to keep it going forward.

I did this through several additions of Red Sea alk over the past few days. Roughly 40 - 50ml in a go, once per day. As expected, the alk would spike up but then it's been falling somewhere between 0.3 - 0.6dkh/day. Have a look at the screenshot from the Trident.

For what it's worth, my sand is not crusty, there's no meaningful precipitate in the sump, nothing accumulated on heaters or pumps, etc. The water clouds up a little when I add the alk to the tank but I add it right in front of a powerhead and it dissipates quickly.

Is my tank really using this much alk on a daily basis? It seems like a crazy amount to me.

 

[Alexreefer]

Hmm weird. I'm no professional at all in the Apex department. But maybe the probe isn't properly calibrated? I

 

[KrisReef]

I see alk going up, not down? Am I reading this backwards?

 

[jlbrew3]

I see alk going up, not down? Am I reading this backwards?

No, not at all. It's absolutely trending up, as desired. It's just dropping back down 0.3 - 0.6dkh/day despite being an empty tank and that's confusing me.

 

[mermaid_life]

Do you think it could be a buffering or balance issue? How is your magnesium?

 

[Alexreefer]

No, not at all. It's absolutely trending up, as desired. It's just dropping back down 0.3 - 0.6dkh/day despite being an empty tank and that's confusing me.

Peaking up after u dose the alk? Then steadily drops. Hmmm rubble be the cause??

 

[KrisReef]

I remember reading that new rock could absorb alk for awhile until the crystal structures in the pores are filled to equilibrium.

edit:
I have a couple of barrels of rock cooking and decided to add baking soda to help with this prospect.

 

[bushdoc]

If by any chance you are dosing ammonia, that it would explain it, otherwise suggest checking alkalinity with different method (salifert)

 

[mermaid_life]

Oh and after getting a Trident, I now know that alk also cycles throughout the day, like pH.

 

[jlbrew3]

Appreciate everyone weighing in!

I have not been dosing ca or mag. Calcium has fluctuated between 480-510 but is generally been stable. Mag has stayed between 1340 - 1350.

I haven't dosed ammonia since the first addition a couple months ago at this point. I have been adding ~30ml of phyto each day for the pods.

Perhaps it is indeed the rubble. I also have bio bricks in the sump that I added around the same time as the rubble. So if they absorb alk when new, that'd certainly be a reasonable hypothesis!

 

[jlbrew3]

I remember reading that new rock could absorb alk for awhile until the crystal structures in the pores are filled to equilibrium.

edit:
I have a couple of barrels of rock cooking and decided to add baking soda to help with this prospect.

There's certainly plenty of pretty new rock and also some bio bricks/blocks. Have you observed falling alk? Not sure if you've been testing the barrels or not

 

[KrisReef]

No. I added it expecting that it might. Some other poster was asking a similar question and the answer was bio/geo/chemical regarding crystal rock structure and pores that have an affinity for alk, until saturated. Your tank seems to showing these symptoms. My barrels don't have any need for alk so I figured I would treat the pores incase the rock was "hungry" for it. like yours is. My wife is calling me to go eat.