New dry rocks-Can they leach out alk and calcium?

[Klyph]

Cleaning it doesn’t help. Stop dosing anything for a few days, Keep alk low 7 dKH when you resume dosing, and use bicarbonate to do it. Don’t aggressively lower phosphate, and don’t use gfo. After a while it should stop if you are feeding and such.

All makes sense. Thanks so much.

Last question... I’ll refrain from cleaning / breaking up the sand bed chunks for now, but am concerned that I’ll create the problem again when I eventually do clean the sand and re-expose the precipitate (say a couple weeks ago, when things stabilize). Will that be a problem in the future?

 

[Randy Holmes-Farley]

The sand will get coated and protected over time.

 

[Klyph]

@Randy Holmes-Farley , follow up question to my situation. My low alk was certainly due to a precipitation problem, as I saw a fall dollar sized clump in the corner of the sand bed. I followed your advice. I waited a couple days, dosed magnesium up to 1400, and then turned off my carbon reactor and protein skimmer (I left my refugium light running at night). I then slowly and dosed baking soda (mix of 2 tablespoon per gallon RODI water), several cups a day for several days, slowly increasing alkalinity from 4.5 to 9.6. I did this by dripping 2 cups, twice a day, via a zip log bag with a pinhole, hanging over the tank. Also got calcium up to 440 thru a less intense dosing regiment.

I was syched! I finally solved the problem. I intentionally went 3 days without additional dosing, with the intent of measuring alkalinity again to determine how much I would need for maintenance dosing. I was expecting 9.0, maybe high 8s. I GOT 6.0!!!! What the heck??!!? Where is all my alk going? (Btw, Calc dropped from 440 to 425, which I assume is reasonable).

I did turn the carbon reactor and protein skimmer (with a recirculating CO2 scrubber) back on during these last 3 days. Could that be the culprit? Do you have any thoughts or advice?


Btw, other numbers are:
Temp 79
Salinity 1.026
Ph 7.9
Mg 1400
Calc 425
Nitrate 6

 

[Randy Holmes-Farley]

The raised pH will help drive precipitation. I might just target 7 dKH for a while.

 

[Klyph]

The raised pH will help drive precipitation. I might just target 7 dKH for a while.

I’ll give that a try. It was so strange, that as I slowly increased it, it was hanging steady... no significant drops between doses. Then somewhere between Sunday and Wednesday, the bottom fell out. There must be a mysterious hair trigger threshold.

One additional question;
At what point should I attempt to remove the existing precipate (i.e. the clumps) from the sand bed? I’m concerned that stirring it up will cause even more precipitation.

 

[Randy Holmes-Farley]

Then somewhere between Sunday and Wednesday, the bottom fell out. There must be a mysterious hair trigger threshold.

That is what happens. Seawater is normally supersaturated with calcium and carbonate. That is, it is poised for precipitation, but the step of getting a crystal started is very slow. Once you get some fresh crystals forming, they act as seeds for more precipitation, and the processe4s accelerates until the supersaturation is gone.

Here's a cool video of the process:

 

[Randy Holmes-Farley]

One additional question;
At what point should I attempt to remove the existing precipate (i.e. the clumps) from the sand bed? I’m concerned that stirring it up will cause even more precipitation.

It will be impossible to remove them as they likely coat the sand. They become coated with organics, phosphate, and magnesium that ruins them as a seed in a few days or so.

 

[Klyph]

That is what happens. Seawater is normally supersaturated with calcium and carbonate. That is, it is poised for precipitation, but the step of getting a crystal started is very slow. Once you get some fresh crystals forming, they act as seeds for more precipitation, and the processe4s accelerates until the supersaturation is gone.

Here's a cool video of the process:

@Randy Holmes-Farley , Hi, it’s me again. If you recall, I had a bad precipitate problem that was dramatically lowering my alkalinity. I asked you whether I should do a partial water change, vacuuming the sand and rocks to try and get rid of any residual precipitate. You told me that was unnecessary. Earlier this week I blew water around the rocks and a bunch of white cloudy water blew off, which I assume was some of the remaining precipitate. And my alkalinity is now taking another dive. I fear I have a ticking time bomb in my aquarium and anytime I disturb the remaining precipitate I’ll have another drop. Is that irrational? Is there a drawback to cleaning the sand, breaking up the chunks that still remain?

 

[Randy Holmes-Farley]

@Randy Holmes-Farley , Hi, it’s me again. If you recall, I had a bad precipitate problem that was dramatically lowering my alkalinity. I asked you whether I should do a partial water change, vacuuming the sand and rocks to try and get rid of any residual precipitate. You told me that was unnecessary. Earlier this week I blew water around the rocks and a bunch of white cloudy water blew off, which I assume was some of the remaining precipitate. And my alkalinity is now taking another dive. I fear I have a ticking time bomb in my aquarium and anytime I disturb the remaining precipitate I’ll have another drop. Is that irrational? Is there a drawback to cleaning the sand, breaking up the chunks that still remain?

It is certainly possible that if you have a lot of fresh calcium carbonate surfaces that are somehow not in good contact with the water (like buried) and then you suddenly expose those surfaces to the tank water, that precipitation event will rev up again. Removing it might be an appropriate option if that seems to be the case.

 

[Klyph]

It is certainly possible that if you have a lot of fresh calcium carbonate surfaces that are somehow not in good contact with the water (like buried) and then you suddenly expose those surfaces to the tank water, that precipitation event will rev up again. Removing it might be an appropriate option if that seems to be the case.

Think I’ll give it a try. Thanks for all your advice.

 

[beefybear]

Sorry for reviving this thread but I have a similar scenario. I’ve had a tank for four years in which I had anemones. At first everything was great (precipitation wise) but within the last 1-2 years things started ramping up. I would have to dose more and more in my anemone exclusive tank and didn’t know why. I thought it was potentially waste product being converted but I’d have to continually ramp up my dosing every month and began noticing precipitation now on the glass bottom and equipment within my tank. It got to the point i was so fed up I decided to go cold Turkey, as in cut dosing altogether to allow the deposits to be covered. Ultimately the tank crashed and inhabitants died, I was so upset and sad that I just stopped for near a year but kept the tank running.

During my hiatus I didn’t change the water but just provided evaporation replacement. I tested the alkalinity every month or so out of curiosity and noticed it continually dropped, it got so low it fell below 4dkh on my Hanna checker. Almost a year later now I did a 100% water change and am getting ready for fish this time. I tested the alkalinity and read 8.4; testing it the next day read 7.5. There are no inhabitants, this tank has been running for years and alk is still dropping points at a time.

My #1 suspect however is the rocks themselves. All over it looks like little beads have grown on the under surfaces, I am convinced it’s the rock that has created so much calcium carbonate surface area that it’s devouring my alkalinity. The rock is BRS Marcorock dry live rock. Just curious if this is a possibility, I’ve thought about ordering a little more rock from brs to compare fresh texture to mine. Tank is a 50 gallon cube bare bottom. Thanks! Any help is appreciated