Cured Dry Rock Lowered Alk?

[IHaveCrabs]

So this weekend I plumbed my 120 (new) into my existing 60g Shallow. Before turning on the plumbing between the two takes to begin mixing the water, I tested and corrected the new 120 to match the existing 60 in Alk, Ca, and Mg.

Mixing started Saturday and on Monday I test Alk and it has dropped to 7.28 from 8.12 in two days! Previous to mixing the two systems, my alk was extremely stable moving between 8.12 and 8.28.

Could it be all the new cured dry rock that is sucking up the Alk?

Thanks for your input!

 

[IHaveCrabs]

Bump - Any thoughts on this?

 

[Sparky312]

Maybe that is possible, but you also tripled the water volume, which would magnify any errors in your readings. All the test kits we have are hobbyist grade and subject to some error.

Its not that big of drop though, I wouldn't stress about it, unless it keeps going down. You might drive yourself crazy looking for the answer

 

[tinman]

Very much possible .. i dont remember exactly but i was reading sometime back ( about year or two ago) how in new tanks its really hard to stabilize the ALk, calc and mag triangle and the major reason is cause the dry rock does suck/leach those elements ....

 

[IHaveCrabs]

Thanks guy. It seems to be stable now.. just low. Working it back up slowly.

I have an awesome piece of SPS that is really sensitive to Alk and when I add 10ml in, all the polyps extend and look happy. if it gets low, he loses PE until it is up again.

 

[Paulip]

My new 14G Nano has a similar problem right now with my Alk dropping 1 dKH daily. Either that or some other imbalance is pegging it to 7-8, probably PH. Somebody, please educate me if this is some other imbalance. I do a 10% WC every week.

I suspect the rapid growth of coralline algae, even at the pre-encrusting stage, is sucking up the Alkalinity. Though, I am getting purple spots at a rapid clip. Did you do a baseline of your magnesium as well? That may also be depleted much more than your used to.