What causes sand to firm up

[RyanCSGO]

i had a dsb on a cube that had a lot of sand get real firm and clumpy. Looked horrible.
I noticed in my new tank it was starting to do the same. I was able to stir up the sand bed just a little bit to loosen everything up

What causes this and how to I prevent it?

 

[saltyfilmfolks]

Like calcium precipitation?

 

[RyanCSGO]

No clue. From bits and pieces I've read that seams like it.
Paranoid about it now.

Alk 8.5
Cal 430
Nitrate less than 5
Ammonia 0
nitrite 0

Picking up a mag test tomorrow. Read that low mag with higher cal can cause it? I dunno...

 

[Salty1962]

Most probably calcium precipitation. What kits are you using for your Alk and Ca testing? You may try and lower your Ca to @390 for a short while and see if that helps. Lower Ca levels for a while shouldn't effect your corals.

 

[RyanCSGO]

Most probably calcium precipitation. What kits are you using for your Alk and Ca testing? You may try and lower your Ca to @390 for a short while and see if that helps. Lower Ca levels for a while shouldn't effect your corals.

Using Lamotte for alk and salifert for cal.
I only dose bionic 2 part. Lowering cal would lower the alk as well, I already have sps in the tank and hardly any nutrients, you think there would still be no effect if I lower it?

 

[Randy Holmes-Farley Verified Community Expert]

How much B-ionic are you dosing each day?

Sand clumping happens mostly in newer systems. Perhaps because there's not as much organic matter coating the sand grains, reducing the chance for them to nucleate precipitation of calcium carbonate.

Clumping of sand may be purely abiotic, but may also be driven by biological processes, and most often happens with new sand.
Reduced precipitation can be reached with lower pH, alkalinity and to a much smaller extent, calcium, and higher magnesium, organics, and phosphate.

Fresh CaCO3 surfaces can be most prone to more precipitation. To break the cycle, it can be useful to stop dosing for a few days, let alk fall and precipitation stop, then restart with a much lower dose.

 

[RyanCSGO]

How much B-ionic are you dosing each day?

Sand clumping happens mostly in newer systems. Perhaps because there's not as much organic matter coating the sand grains, reducing the chance for them to nucleate precipitation of calcium carbonate.

Clumping of sand may be purely abiotic, but may also be driven by biological processes, and most often happens with new sand.
Reduced precipitation can be reached with lower pH, alkalinity and to a much smaller extent, calcium, and higher magnesium, organics, and phosphate.

Fresh CaCO3 surfaces can be most prone to more precipitation. To break the cycle, it can be useful to stop dosing for a few days, let alk fall and precipitation stop, then restart with a much lower dose.

Started out dosing 12ml a day (6 doses, 2ml ea every 4 hours)
which held the following:
alk 7.9
cal 450

since I have no nutrients in the system currently I wanted to adjust the numbers slightly
bumped it up to 18ml a day (6 doses, 3ml ea every 4 hours)
which now gives me the following
alk 8.5
cal 430

on my way home from work I am picking up a mag test as well

last night I backed it off from 18ml to the 12ml schedule again

should I just shut it off completely for now?

Salinity always 1.026
currently in the tank:
x1 - yellow coris wrasse
x1 - yellow tang
x1 - diamond goby

x1 - 4 head aussie torch
3 inch green slimer
1 inch green slimer
2 inch purple stylophora
2 inch monti cap

note, the sand is new, fiji pink.

also, my skimmer still does not function properly (could still be breaking in or maybe i just do not have anything for it skim?)
it just overflows no mater the water height
I added a small bag of GAC to see if it would pull anything out of the water that may be the cause

 

[Randy Holmes-Farley Verified Community Expert]

Dropping back substantially on the dose (to reduce alk and pH) and switching to baking soda for the alk part (to reduce pH) for a while may help reduce the clumping.