Help sand turning to concrete!

[apexkeeper]

So I recently noticed my sand has been getting really hard. Almost like it's turning into concrete. What the heak is going on?

My sand is seaflor special grade and has been fine for the past 6 months. The only real change I've made to the tank is I started to drip Kalkwasser for my top off. That can't be a coincidence.

I drip aprox 200ml per hour of full saturated (2 teaspoon per gallon) ESV kalkwasser.

My parameters are

PH - 8.3
Alkalinity - 10
Calcium - 420
Mg - 1440

And I have a bunch of nassarius snails which usually keep the sand bed stirred up.

Anyone know whats happening and what I should do?

 

[Sk8r]

Could you have an expired alk test?

 

[cloak]

I always thought that the hardening of a sand bed had something to do with the pH, but I might be mistaken. If you haven't already, you might want to post this question in the Reef Chemistry forum. Somebody there should be able to give you a very detailed answer regarding this. GL.

 

[ghellin]

I agree with sk8r, have a lfs run a test for you. Don't tell them what you are looking for or your concerns so you can get fair and honest results. I add the last part as some stores prescribe based on your personal diagnosis.

 

[apexkeeper]

I'm gonna take some water over my buddies house tomorrow to have him triple check my numbers with his kits. I use Redsea (except for PH which is API) my buddy uses salifert for everything.

I just did another PH test with a different bottle of solution and got the same numbers, and the date on my alk kit is still good.

If it matters everything else with my tank is awesome, my corals are thriving, my fish are healthy, zero algae issues, nice coraline growth coming in, I keep up with all maintenance and water changes. etc

 

[ca1ore]

I dunno, I guess I have always found that over time, in the absence of sand stirring animals, that it does clump up. You should be able to break it up with your fingers though.

 

[Panta rhei]

Hi, any other change like carbon dosing or new fish(es)?
I'm asking as one of the reason of the hardening of the sand is the association of bacteria and the lack of the smallest sand benthos.

 

[apexkeeper]

Hi, any other change like carbon dosing or new fish(es)?
I'm asking as one of the reason of the hardening of the sand is the association of bacteria and the lack of the smallest sand benthos.

Nope, haven't done any carbon dosing or changed anything else. Last livestock addition was over 2 months ago, just a small green hairy mushroom and some zoas. My tank has a pretty light bioload.

 

[apexkeeper]

Well I had my water parameters double checked on different test kits. Everything is pretty close to matching

Alk - 10dk
Ca - 405
Mg - 1420
PH - 8.2

 

[curthendrix]

It's the kalk addition imo. I've seen it happen to several tanks. Kalk is calcium rich with high PH...the perfect ingredient for sandbed solidfication.

 

[apexkeeper]

So is it necessarily a bad thing? I'm in the process of switching to 2 part dosing but was going to continue using kalk for my topoff. Should I just ditch the kalkwasser?

 

[Dan_P]

How old is the tank when you started adding kalkwasser?

Precipitation of calcium carbonate is the likely culprit, though calcium phosphate is another precipitate that could be forming with kalkwasser additions.

I found something interesting and probably totally irrelevant while researching cyanobacteria. Bacteria that coexist with cyanobacteria in mats form calcium carbonate sand, more so when the cyanobacteria is dead. So, have any cyanobacteria die offs lately

 

[apexkeeper]

I just checked my log book (yes I keep a log book of my tank, don't laugh...)

I started dosing kalkwasser july 7th, the tank was 132 days old at that point. So about 4 and a half months old. I started with 1 teaspoon per gallon and 225ml per hour. September 14th I increased to 2 teaspoons per gallon and 225ml per hour. And I noticed the sandbed issue started a little over a week ago.

And no cyano or other algae. I had outbreaks during the first 2 months but everything cleared up and has been great since.

 

[curthendrix]

I believe Kalk is beneficial for a reef tank. I also believe that one must be careful in it's use. Watch your calcium, alk and PH levels. I had used Kalk for years and just recently dumped it and went soley to calcium and alk additives only as I continued to have issues with my sandbed solidifying.

 

[Dan_P]

I just checked my log book (yes I keep a log book of my tank, don't laugh...)

I started dosing kalkwasser july 7th, the tank was 132 days old at that point. So about 4 and a half months old. I started with 1 teaspoon per gallon and 225ml per hour. September 14th I increased to 2 teaspoons per gallon and 225ml per hour. And I noticed the sandbed issue started a little over a week ago.

And no cyano or other algae. I had outbreaks during the first 2 months but everything cleared up and has been great since.

I won't laugh because I keep a daily log myself!

Increasing the kalkwasser amount might be a clue to your substrate solidification. Check your magnesium level too. Magnesium inhibits calcium carbonate crystal growth.

This might be a good topic for the chemistry forum.

 

[James77]

I have had the exact same problem when using 2 part, the one with the higher pH. I also found that I was needing tremendous amounts of it, even though the tank should not have required that much. The sand was also that Seafloor Special.....not sure if the problem is unique to it.

It was the spike in pH that was doing it, I alleviated it by switching to the lower pH recipe. I would try dripping your kalk over a longer period or dilute it more...or both.