Top layer of sand rock hard and alk/ca dropping

[Lividfanatica]

First off, my parameters:

310 Gallon display
ALK 7 dkh
CA 390
Mag 1400
pH 7.9-8

My tank is pretty new, only a few months old and I am dosing about 7 liters of saturated kalkwasser and 200ml of sodium hydroxide and 200ml of calcium chloride per day to keep up with “demand”. There are barely any frags in the tank and no visible coralline growing. I have been struggling to find the source of the uptake as no precipitation is visible until today…. I just added some snails and in the process of righting them, I found the sand bed is ROCK hard at the surface. I am guessing this is where all my Alk and CA are going. The sand is aragalive special grade “live” sand

Any thoughts on what to do? I can manually stir/break up the sand. Do I keep trying to maintain my alk and Ca levels?

@Randy Holmes-Farley i thought to post this in your forum, but I’m not sure this is a chemistry problem… please chime in if there is a chemistry issue here.

Attached is a photo of chunks of sand I broke up.

 

[homer1475]

100% chemistry issue.

Stop dosing everything, and get it sorted out. Ask me how I know.....

 

[homer1475]

That is not rock, but my sandbed after a dosing accident.

 

[Lividfanatica]

100% chemistry issue.

Stop dosing everything, and get it sorted out. Ask me how I know.....

How did you correct it? I was able to bust up the sand by hand (only got about a third of the tank done). I have turned off all the dosing, but there is some coral in there so I don’t want to let everything bottom out.

 

[Randy Holmes-Farley]

New sand that is missing a coating of phosphate/magnesium/organics/bacteria that all prevent precipitation of calcium carbonate, along with high pH and high alkalinity are the usual drivers of hardening sand. Old sand can also experience it.

Here's my usual recommendation:


1. Stop all efforts to boost pH.
2. Stop dosing alk for a bit and let it decline.
3. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
4. Ensure magnesium is normal to high.
5. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

 

[Lividfanatica]

New sand that is missing a coating of phosphate/magnesium/organics/bacteria that all prevent precipitation of calcium carbonate, along with high pH and high alkalinity are the usual drivers of hardening sand. Old sand can also experience it.

Here's my usual recommendation:


1. Stop all efforts to boost pH.
2. Stop dosing alk for a bit and let it decline.
3. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
4. Ensure magnesium is normal to high.
5. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

Thanks! I have discontinued dosing and my ph has leveled out at about 7.8. Alk has stabilized a bit below 7 and Ca seems to be staying up near 390. I started manually crushing up the sand, but I can only do about a third of the tank at a time before my hand feels like I just got done petting a porcupine.

At least I got my scuba/snorkel fix in.