Precipitation problem

[Davey-Jones’-Locker]

Hey y’all, I’m having an issue with precipitation in my sand bed. I dose 48 ml of BRS calcium (2ml every hour on the half hour). 48 ml of BRS alkalinity (2ml every hour on the hour), manually test and dose Magnesium weekly and have an ATO. I’ve noticed that I’m getting a lot of chunks in the sand bed and especially around my live rock the sand has turned to rock. My return pump and area where the dosing line drops the ALK is developing a lot of precipitation as well. Any suggestions on how to reduce this? Also let me know if you need more info

 

[Davey-Jones’-Locker]

Ph stays around 8.1
Alk averages 7.9
Calcium 450
Mag 1320
Nitrates 1-2
Phosphate .2

 

[Randy Holmes-Farley]

Here's a copy and paste from a similar situation:

I would not be certain the issue is ongoing precipitation, but it might be. Sand clumping does not prove it to be currently happening. Sand hardening happens initially when the tank is set up then slows as the sand becomes covered in organics, magnesium, and phosphate, but here is my standard recommendation to reduce precipitation on sand, heaters, pumps, etc:

If you are concerned about abiotic precipitation, then ways to stop it are:

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