What causes clumping sand?

[Fishamatank]

Just like the title says....
I get clumps of sand about the size of small gravel that accumulate pretty quickly. Nitrates, phosphates are undetectable. Alk is 10-11, ca around 460. I use DIY 2 part via dosing pumps. No cyano, HA, or other problems related to nutrients.

 

[bertoni]

Nobody's sure, but the process seems to stop in tanks after they've been up for a while. Are you dosing a high-pH alkalinity supplement? They could in theory encourage precipitation.

 

[tmz]

No one knows . Bacterial activity and/or high alkalinity are the usual suspects.

 

[outy]

Ive been dosing 14 years and noticed sand clumping in the beginning.

I now run a calcium reactor, has anyone noticed with a reactor they dont get the clumping?

 

[tmz]

The reactor would lower ph generally which might discourage precipitation of calcium carbonate.

 

[Fishamatank]

Yes, I use high ph 2 part and I top off with kalk.
Should I try lowering the alk?

 

[HighlandReefer]

As stated above there are several possible reasons for sand clumping. There are micro-organisms like bacteria that will precipitate calcium carbonate which can cause sand clumping. If this is causing it, then changing alk supplement will not help. IME and Randy's experience the sand clumping occurred in new sand beds. I removed the clumps and have not had any more since. The same with Randy. Both Randy & I use kalk water for supplementing. Perhaps kalk water may have something to do with it, but many hobbyists that experience sand clumping use two-part.

 

[HighlandReefer]

You may want to shoot for an alk level in the middle of the recommended range like 9 dKH. Alk kits are notorious problems. If you are using a alk kit designed for freshwater, which many are, then you alk level is higher than you think. Your alk level is 10% higher using a fresh water kit, so if you keep an alk at 11 dKH, then your true alk is over 12 dKH, which can cause a lot of abiotic precipitation.

 

[bertoni]

I agree that lowering the alkalinity might help. If the pH is running on the high side, switching to a lower-pH supplement might help some, too. Most often, the problem seems to go away on its own, from what people have said.

 

[tmz]

Cleaned my frag tank with a sand bed last week, It has been up for about 4 yrs. Early on there was heavy clumping. Ph and alk were relatively high then. Alk has been much lower over the last 2 years . Still when I reached into the sand there was significant but lesser clumping.

 

[Boomer]

I think I have explained this before. In Sedimetentology we call this "Early Marine Diagenesis"

1. The local water in the SB develops a low pH from activity. This causes the dissolution. As dissolution continues the local pH, Alk and Ca++ begin to rise and reaches saturation, causing the precipitation of some CaCO3 around the grains "welding" them together.

2. Fresh new carbonate sands, like in a new tank, are not in equilibrium with the water. This causes the direct precipitation of calcite and often Hi-Magneisum Calcite on the the sand grains surfaces " welding " them together. There are many paper written on this and it is this that is more than likely what is happing in new tanks with new sand bottoms of carbonate sands.

3. Excessive Ca++ Alk and high pH can also cause this, as the sand favors more to precipitation in the SB, which will be even greater if the temp is a little higher there.

The above three produce a cement like clumping structure, where the grains can not be separated without hammer in hand.

4. Certain types of high SB bacterial activity produce organic "slimes / glues" that stick the sand grains together. In this case of SB clumping the grains can be pulled apart. The are more like a sticky cluey mess.



Forgot

Kalk with vinegar or other types of carbon dosing could make this worse where there may be more than one thing going on.

 

[Fishamatank]

this sand is 1 year old, is that still "new"?

 

[Boomer]

NO, that is pretty much somewhat old sand. Is the sand like cement or can the sand grains be pulled apart ? More than likely in your case it is the high Alk and Calcium # 3 There is NO reason for them to be that high.

 

[Fishamatank]

The sand clumps are pretty hard, not cement hard, but difficult to break apart by hand.

Typically I have 20 or so chunks the size of grapes that I siphon out every 2 weeks with water changes.

I will cut the dosing pumps back a bit and see what that does. I have kept the alk / ca on the high side for several reasons: to compensate for errors in testing, to give me a buffer of a couple days should something go awry with the dosers, and it seems to encourage faster growth.

 

[bertoni]

Higher alkalinity and pH often will encourage faster growth, but I agree that they might encourage sand clumping.

 

[Fishamatank]

Little OT here, but I tested ALK with two test kits.
Elos = 9
API = 11

Is either one of these known to be more accurate than the other. 9 is really not any higher than most run, but 11 is on the high side.

 

[bertoni]

I wouldn't trust the API kit if it's more than a year old, at this point. Can you locate a date on it? Or on the Elos? Those numbers are fairly close, given the problem rates that get reported on alkalinity test kits.

 

[Fishamatank]

They have both been purchased within the last 6 months.
Nothing on the Elos kit, the API bottle says lot 59A0909, I am going to take a wild guess and say that indicates September of 2009, but who knows.

 

[bertoni]

I think you're right. Well, if you have a higher-end pH meter, you can do a DIY alkalinity test, although you'll have to buy a standard acid. The meter should read down to .01 pH units, hopefully with accuracy close to that, and accept pH 4 and 7 calibration solutions. I can post a link to details, if you're interested. Sorry I don't have a better answer.

 

[Fishamatank]

Yeah, I've seen that info before, just seems like a little too much work. I'll just go with the average of my two kits and call it 10. I'll shoot for lowering it down to 8.5 or so with a Ca of around 400. Hopefully that will stop the clumping.