Live sand absorbing ALK, Ca, and PO4?

[Waters]

This is the second tank I have used Caribsea Live sand and have had this issue. When tank was initially set up, my ALK and CA requirements were triple what I normally would need in a 100 gallon tank. I was dosing upwards of 140ml daily just to keep numbers even close to 8 ALK and 440 Ca, with very little coral. At the same time, I could not keep phosphates in the tank....I would triple dose daily and they would be gone the next day. This went on for almost 6 months. I would stir the sand almost daily, except for the areas that were directly under the live rock. Fast forward 9 months later, I decided to remove my substrate. Within days, my ALK and Ca requirements dropped down to 60ml daily and I no longer have to dose PO4. Also, directly under each piece of live rock, the sand turned to concrete, fused to the rock. I liked the look so I left that in the tank but removed the rest. What process causes the sand to absorb so much ALK and Ca to cause it to harden and fuse together? I see threads all the time about new tanks that can't keep levels up....I wonder how many of these are associated with the sand bed?

 

[ajm83]

I had a similar problem, I was using not their live sand but their 'seeded' dry sand Caribsea Seaflor Special and Caribsea Liferock. No idea unfortunately on the cause.

Tagging along for more info though.

 

[fragit]

I had the same issues with their Special Grade!

 

[arking_mark]

It's reffered to as abiotic precipitation. It's natural and happens more with higher pH and/or higher Alk systems.

 

[Waters]

That is strange then....my system PH was never higher than 8.0 and ALK remained under 8, even with a ton of dosing. It appeared everything I was dosing was going straight to the concrete being formed lol.

 

[Cheeze]

Tagging along too!

My tank has been cycled for 4 months now but I used Tropic Marine dry sand, and am having trouble keeping Alk and Calcium up. All my other parameters are normal tho.

I threw in a bunch of nassarius snails to keep the sand stirred.

 

[Randy Holmes-Farley]

That is strange then....my system PH was never higher than 8.0 and ALK remained under 8, even with a ton of dosing. It appeared everything I was dosing was going straight to the concrete being formed lol.

Raw calcium carbonate will act as a seed crystal for precipitation under those conditions.

 

[Randy Holmes-Farley]

Tagging along too!

My tank has been cycled for 4 months now but I used Tropic Marine dry sand, and am having trouble keeping Alk and Calcium up. All my other parameters are normal tho.

I threw in a bunch of nassarius snails to keep the sand stirred.

I would not assume it is other than ordinary demand. Even snails use calcium and alk to make shells.

 

[Drewbacca]

How can I FIX this tho?
THIS IS MY Nightmare ...I've been living. The back left corner of my 90gal tank is a 1" thick 7x8" rock that is fused to the glass and the rock base it runs into. other rock bases have 2-3 inches bigger than they really are.
Dosing 225 ml a day Each of Cal & Alk to keep 7.5dkh. And Cal 440 but keeps slowly dropping.
Is there anything I could inject using a syringe that will help weaken or loosen this?
It makes cleaning impossible and can't remove base rocks. I took all other rocks out for peroxide surface scrub & siphon/scrubbed all the remaining submerged to try & beat briopsis.. but it was days wasted because even with heavy scrubbing & scraping its stuck growing on This hard sand which gives them perfect rooting.
I need to add new sand I have been seeding with bacteria in 10 gal tank but I dont think just adding it on top and covering is a good idea. I WANT the cement sand and briopsis/turf algae gone.
(the overflow also has a rough texture the briopsis loves. To root into and will grow back right after razor scraping.
I am probably going to need to take out my 3 remaining fish and drain the tank.. remove san & pour something on the botom to allow a scraper to seperate it from the glass.

This IS My Last Stand.. I cant keep spending All my time trying to get this tank back on track.
A zero nutrient induced outbreak of every possible algae/bacteria.. and the fight to beat it.. will reveal the flaws in EVERY Area of your tank.
I have 1/3 of the rock that was in the tank 2 months ago.. in the little tanks with the new sand and bio Spheres ...all getting seeded. (Rock was externally scrubbed
h-peroxide) .. and then in a bucket w heat & flow.. was going to put back in once briopsis was gone... ... ...)
I basically should be able to just drain & removal ALL.. clean tank..& just add These back in with water & fish & coral..
.. and not have to clean newly removed base rocks before putting all back in. ?
Sigh. Shldnt be this difficult.

 

[Randy Holmes-Farley]

It appears you are getting substantial abiotic precipitation of calcium carbonate.

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:


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.

 

[arking_mark]

I periodically try to just break up the sand with my hands or a sharp object. It hasn't gotten to cement-like quality. Now I've never tried to move my base rock...so I may have cement sand there.