What glued my sandbed

[Covey]

Hello,
I went to net out a fish add to pull most of My LR. I discovered that my sandbed is rock hard. I always thought that I was using alot of Cal/Alk Buffers. The bed was new when I moved 8 months ago. My question is there any type of Cal Alk system that is more or less likely to cement a sandbed based on chemistry?

As demand increased I ending changing method a few times and I am wondering if one is any more like than another to cause this.

As demand went up the method changed:
B-ionic(got too expense)
Kalk(Ms. Wages)
Kalk with vinegar
Kalkw/vinegar and b-ionics(still not enough)
Dry powered Seachem Buffers (Reef Builder and Reef Advantage Calcium 1.5TB alternating day.)

I went thru all of this just to keep Cal over 400ppm and Alk over 3meq. I ended up biting the bullet and just getting a Calcium reactor. So it is moot at this point but was wondering what caused the concrete so I can avoid it next time?

 

[speakerguy]

*cough* Don't use a DSB *cough*

 

[ronkent]

<a href=showthread.php?s=&postid=6811492#post6811492 target=_blank>Originally posted</a> by speakerguy
*cough* Don't use a DSB *cough*

Was that necessary? This person is looking for advice on his sandbed not asking whether dsb is better than barebottom. Go bother someone else troll.


Sorry Covey I don't have the answer for you. Do you keep any worms/snails in your sandbed? The nassarius snails are great for keeping the sand grains moving around making it less apt to 'cemeting'. I personally though use kalwasser in my topoff and if i need adjustments I use Turbo Calc and Superbuffer DKH. I have read before that if your chemistry gets way out of wack it can cause your sandbed to cement. I may be wrong though.

 

[speakerguy]

Go bother someone else troll.

OK Mr. Netiquette...

Mineral accretion is inevitable anytime you're using a substrate that acts as a buffer. It will constantly be dissolving and reforming, eventually clumping or forming solids. So if you don't want to happen, don't use a sandbed.

As to what may make the process more or less likely to occur (given that it's already going to occur to some extent no matter what), read the sections on CaCO3 precipitation in one of RHF's articles here:

http://reefkeeping.com/issues/2005-07/rhf/index.php#12

That should give you some ideas as to what may be causing it in your case. But nevermind that. I guess I'm just a troll.

 

[Covey]

Thanks both of you. I am still hoping to here Randy's take.

 

[bertoni]

Our substrates don't function much as a buffer, IMO, and I personally don't think there's much forming or reforming, either. I would guess the sandbed hardened because of calcium carbonate deposition, possibly due to high pH or too much supplementation, or because of a lack of animals "stirring" it.

I don't know of any studies that show conclusively that one or the other reason is more likely, etc., so some guessing is involved. How deep was the sand, and how was the tank stocked? Likewise, have you had any high calcium-alkalinity or pH issues?

 

[wet reefer]

So, does stirring it stop the chemical reaction causing it?
Seems to me the reaction would still occur.

 

[cwegescheide]

FWIW my reef chemistry was WAY out of whack for quite a while (unknowingly) in my first attempt at a reef and my sand never turned to concrete. This reef was up over 2 years. I had normal run of the mill sand in this tank..

My current reef, got a new custom tank all the whistles and bells and really wanted to make sure I was doing everything right. When I set my tank up I put ARAG-ALIVE corse sand (I run Tunze's in my 90 thinking this might not blow around as much) and no other kind of sand, just the arag-alive. When I first set it up my chemistry was a little out of whack, my alk got a little high. at one point it was 4.8 meq/l at one point which I aim for 3 to 4 meq/l according to Randy's advice.. Well one good thing is I don't have to worry about my sand blowing around. Why because its hard as a rock!!!! Personally I think its something with the arag-alive sand..

I'm by no means an expert but this has been my experience. I'd be curious what everybody's substrate was that turned to stone..

 

[bertoni]

I didn't post a very good explanation...

The idea behind having animals "stir" the sand is that it prevents bacteria from "gluing" the particles together. That's the second thought behind solidifed sandbeds, since bacteria are known to bind particles together in that manner.

I suspect that the stirring (bioturbation, technically) might also help with deposition by breaking apart particles before they can become firmly cemented, but that's only a guess.

 

[wet reefer]

Right. I agree, but IMO sand beds act as a carbonate, calcium and magnesium sink if alk levels are high (more than natural seawater @2.5mq.) The link to Randy's artical explains this. In fact, I would think that stirring the sand would increase this effect. More surface area being exposed or available for the reaction or precipitation to occur. Maybe off the subject, and I dont really want to turn this into a DSB debate. Besides I could be completely wrong!

 

[wet reefer]

I will say this though. I have been slowly removing my sand bed (not a DSB). I am adding alot less 2 part mix to my tank now. I'ts not hard taking it out...it comes out in bricks!

 

[Randy Holmes-Farley]

It is not entirely clear whether sand bed hardening is a purely physical process involving calcium carbonate deposition (or other minerals) that cements grains together, or whether it is mediated by bacterial processes, but it does not always happen by any means.

It happens most frequently to new sand, and especially when the pH is high (as when using limewater). It happened to me when I first set up my first tank, but not when adding tanks to the existing system using the same type of sand. I would guess that higher alkalinity and calcium also contribute, as well as lower magnesium.

Often the effect disappears as tanks mature (the hard sections stay hard, but unclumped sand stays that way, and new sand won't as readily clump).
The addition of organisms (cucumbers, etc) seems to delay or stop the process as they keep it mixed up and perhaps break tiny links between grains before they become too established.

 

[Covey]

I was surpised that it happened so quickily. It was new sand 8 months ago and now it is a brick. My real question kinda got lost in the jumble in that was anyone method of adding Cal/Alk anymore likely to do this versus another. Is say Calcium Hydroxide more likely do it versus say Calcium chloride?

Like I said I was only trying to maintain Cal at 400ppm and Alk above 3 meq. I was barely holding it there so I don't think the levels where excessive. I didn't have a Mag test thru most of this but when I did get one my Mag was at 1150ppm I think. If that helps.

 

[Randy Holmes-Farley]

My real question kinda got lost in the jumble in that was anyone method of adding Cal/Alk anymore likely to do this versus another. Is say Calcium Hydroxide more likely do it versus say Calcium chloride?


Yes, it appears that limewater is the worst case, probably because it raises pH the most.

 

[Covey]

thank you!

 

[Randy Holmes-Farley]

:thumbsup:

Happy Reefing.