Sand bed gone hard (cement)

[Allmost]

Hello again.

so I was traveling alot last couple of months, and my dosing was done by friends, and well was not accurate, last month I noticed that the sand bed in the display tank (about 3") has gone hard on some parts !!! like cement.

so I assumed that something is a miss with MG causing CA and KH to precipitate and stick sand grains together, checked everything, corrected the dosing and changed my salt mix. from reef crystals to tropic marine reef pro.

at the time sand went cement :
KH was about 9
CA at about 380
and MG at 1300
the KH of Reef crystals is 13 !!!! so at every water change, the KH jumped to 11 and then down !!! maybe this was causing ISsues with the sand ? )


I have since then corrected everything and here are the readings now :
KH at 7
CA at 420
and MG at 1400


now what do I do ? the sand bed is still cement like :S

would this have any bad effects ? I can try to break up the large pieces every once in a while, but am worried it would release too much bad stuff.
any advice ?

I really dont want to take the tank down just to replace the sand bed, lol


any advice is appreciated.

[Boomer]

This, at times, is a common issue for some.

1. In geology it is called "Early Marine Diagenesis", same for # 2.

Yes, you are correct to a degree. Fresh carbonate surfaces love to attract and deposit what is called Hi-Magnesium Calcite. If the sand is somewhat fine and little bioturbation by critters the the grains stick together giving "cement".

2. If the local pH around the grains gets low, they start to dissolve, as dissolution takes place the local pH, Alk and Ca++ rises, reaches sat, now causing them to leave solution as a precip binding the grains together.

3. At times the grains get a dense population of bacteria due to low or poor bioturbation. These bacteria produce a "glue" like substance that glues the grains together. However, this is different than the other 2, as the grains can be pulled apart, as it is not a cement like nature.

4. Another suggestion has been the excessive use of Kalk in new systems.

There is nothing you can do but remove the cement "clumps" and start over so to speak or try to break up the pieces to see what happens.

[Allmost]

hmm I see, thanks,

I tried to break up some of the clumps, and they can be broken down fairly easy actually, (in water) just playing with it in my hand broke it into sand grains.

now its not bothering me, since I can have more flow now lol but is this something bad for the tank live stock ?

I guess depending on which of the 3 you mentioned happened it will either continue to happen or has stopped already (if due to low MG) I dont dose kalk, and well this tank is less than 1 year old, so Im not sure if that's enough time for the bacteria glue to form,

also, its not 100% of the sand bed, just parts of it (specially the parts getting most flow ! )

hmmm cant figure if this is a big problem I should act on ASAP and replace the sand bed with new dry sand (which would cause some diatom algae I guess) or should I over time break up or remove larger pieces.

also, this sand bed is really active ! I see alot of worms and stuff in it at the same time.

thanks again boomer, really enjoying all the chemistry here :) although my GF doesnt since I spend most of my time after work reviewing my chemistry books and lookin up parts of your posts that I didnt know about :)

[myaerica]

I had this happin in my tank I did it on purpose kept the ph really high with kalk. Now the sand dosen't move around in the strong current.Sps love it sand stays put.

[Allmost]

I had this happin in my tank I did it on purpose kept the ph really high with kalk. Now the sand dosen't move around in the strong current.Sps love it sand stays put.

LOL YES !

I can finally turn my MP40 all the way up :)

wow glad to hear its not causing Issues.

[Boomer]

now its not bothering me, since I can have more flow now lol but is this something bad for the tank live stock ?

Me love flow as long as it is not to excessive :)



also, its not 100% of the sand bed, just parts of it (specially the parts getting most flow ! )

Hmm, that is rather odd but more than likely may follow #1 . None of us have ANY exact reason or data as to how this is occurring in reef tank x, y or x. It is all more or less based on Marine Sediment Biogeochemsity/Geomicrobiology where these things are know to happen.

also, this sand bed is really active ! I see alot of worms and stuff in it at the same time.

Then it may just be the way the water is moving through the SD, where #1 is not necessarily tied to critters. In #2 flow should make a difference.

GF doesnt since I spend most of my time after work reviewing my chemistry books and lookin up parts of your posts that I didnt know about

No GF or wife her but I spent way to much time in those books or on the net looking up things for people but that is what I like to do. Hopefully, I do it right or hopefully I get things rihgt :lol: We are ALL here to learn. I always like it when when goes to the books or on-line to check others work. I do it myself allot.

[myaerica]

Yep mp40's are turned all the way up here. I spiked the ph before anything was in the tank but still I have no ill effects one year later.

[Boomer]

So, are you saying the top sand layer is a broken crust so sand under it does not blow around ?

[myaerica]

Pretty much the whole sand bed is clumped together. It has the look of A sand bed but it dosen't move.

[DJREEF]

He has the calcite equivalent of a BB tank.

DJ

[Boomer]

Then I would assume it is pretty much of a waste for its intend function, correct ? Why not just use the "Epoxy Sand-bed Method", which many are using now.

[DJREEF]

Then I would assume it is pretty much of a waste for its intend function, correct ? Why not just use the "Epoxy Sand-bed Method", which many are using now.

Hard to say. It may simply act as a giant slab of LR, assuming that water can still penetrate through the pores. Either way, it's not functioning as a DSB anymore.

DJ

[CorkPullerPHL]

epoxy sand bed? wow, how did i miss this. What a good idea. Sand bed look without the issues. BRILLIANT!

...sorry for the hijack.....:worried:

[jc-reef]

This is a very interesting thread as I am having similar issues as the OP with clumping of the sand. My tank is also new (5mo) and been dosing kalk shortly after cycle due to high CO2/low pH issues (new home). I have a courser/larger grain sand than the fine silicate. I wonder if I am experiencing one or a combo of the issues Boomer described above. I am in process of ordering a DIY CO2 scrubber, so I can reduce the kalk saturation...hopefully this helps.

Tagging along.