Abiotic Precipitate in the Sandbed

[x19]

I've been struggling with keeping my Alk up at target and after a week of looking I think I may have found the source. I've got rather large clumps in my sandbed and I think this may be abiotic precipitation.

Parameters:
Calcium: 465 (Target 465)
Alk: 12 (last night) 11 (this am) (Target 12.6)
Mag: 1380 (Target 1390)
Nitrate: 0
Salinity: 1.025

I dosed 60ml of BRS Alk solution last night between the 12 dkh and 11 dkh readings so that should give you an idea of how much it really used. I can't seem to find my Ph test kit and will pick up a new one today. My Ph has always been constant around 8.1.

My question is how to I stop the sand bed from sucking up my Alk? Do I just remove the clumps or wait it out as this is a new tank? Is there some other process that is eating my Alk that I'm not considering?

Thanks.

 

[little_fish]

Holy crap, that is really high alk reading. 12 should be max, but more in the 9-11 range. That is why its precipitating out.

 

[Smitty]

Do you have any sand stirrers to break it up for you, if not, then yeah, I'd break it up. I know cal and alk has a crazy balance...it seems like the higher the cal, the lower the alk, and vice versa. The only thing I know that'll consume alk quickly is sps corals...you'd be surprised how fast they absorb it.

 

[x19]

Holy crap, that is really high alk reading. 12 should be max, but more in the 9-11 range. That is why its precipitating out.

I'm following the red sea coral pro growth program, which has the Alk target at 12.6. What's interesting is that I am not get precipitate on my heaters or pumps. Its just these clumps in the sand bed.

Do you have any sand stirrers to break it up for you, if not, then yeah, I'd break it up. I know cal and alk has a crazy balance...it seems like the higher the cal, the lower the alk, and vice versa. The only thing I know that'll consume alk quickly is sps corals...you'd be surprised how fast they absorb it.

I've got nassarius snails, and you can see the path through the sand that they take.

 

[marcah]

+1 smitty . it is amazing how much they do absorb...

 

[x19]

+1 smitty . it is amazing how much they do absorb...

I've certainly got SPS corals, a couple of colonies and a few frags but they absorb calcium and alk at 10ppm Ca to 1.4 dkh of Alk ratio. I'm not seeing the requisite drop in Calcium that I am seeing in Alkalinity.

 

[x19]

I'm essentially seeing 3.7 dKh drop in Alk for a 20 ppm drop in Calcium daily. I should be seeing about a 2.8 dKh drop for that amount of calcium. Even that though, seems really really high for a 100 gallon water volume...

 

[Smitty]

Not necessarily true...for awhile, my calcium didn't seem to budge while my alk was being drained...them all of a sudden, the calcium started going down with the same rate as the alk. The corals are just having a higher demand for alk right now, than calcium.

 

[marcah]

the only dosing I do since adding SPS corals is kalkwasser.. Done in correct proportions will maintain the calcium and the alkalinity in desirable limits..
Just make sure when dosing kalk to also keep an eye on your PH because it will raise the Ph of the tank when dosing regularly.. I end up dosing 2 20oz. cups daily to keep my ph at 8.2 to 8.4, always watch to make sure that the PH never goes above 8.4 when dosing it.. my calcium hovers around 480 while my alk is just over 10.5..