what causing this to happened?

[angelfish]

Boomer,

few areas of my RT's sandbed have hardened and turning to concrete.

5" Carribsea Aragonite sand has been in the 75 gal for about 4 years +. recently trying to change to finer grade sand, and these are what i found :

 

[Curtswearing]

What method of Calcium and alkalinity additives do you use?

Additionally, where do you add it and how quickly?

 

[angelfish]

hi Curts,

i'm using CaCO3 reactor fill with ARM @ pH6.5

Seachem Reef Advantage Calcium & Kent Marine Superbuffer dKH for supplementary buffer if either of the reading falls. i dose them about 12hrs apart and nvr together

readings:
pH =8.1(morning), 8.3(evening)
alkalinity = 8~9
calcium = 380~400
Magnesium = 1260~1300

 

[Boomer]

Although what you have does happen it is not that common and there are a number of possibilities.


n systems that have heavy increases in available carbon and nitrate, clumping may occur. This clumping has been reported to be due to precipitation of calcium carbonate and/or Calcium phosphate, but according to Dr. Ron, is most often due to a glycoprotien produced by the cell walls of some spp of bacteria during rapid growth. It is thought to produce enough adhesion between granules to be able to form cement-hard clumps. Such clumps would limit diffusion of the water column and its nutrients into the sandbed, resulting in disaster for the sandbed benthos and the water column of the tank as well. In taking the maturity of the sandbed to the next level, prevention of this clumping is the result of the benthic creatures we cultivate, the macro- benthic infauna: bristleworms, spaghetti worms, bitlles mini-stars, and the miscellaneous other tunneling sand creatures. It is their movement through the sandbed that prevents the clumping and moves the nutrients through their tunnels that aids in increasing the capacity of the sandbeds. They do this without disturbing the oxygen gradient needed for the anaerobes deep in the benthos to be able to process nitrate for us so effectively. Additionally, many of these infaunal animals ingest some sediments as they go. They digest the microorganisms off of the sediment, opening new space for bacteria to grow.

I quote from Dr Shimek again:

Quote:By moving through sediments, the animals jostle and move the particles. Not much, just a little tiny bit. It has been estimated that each day each small organism moves about 10 to 100 cubic millimeter of sediment. Multiplying this tiny average amount of jostling by the number of animals in the tank gives the total amount of disturbance. In my 45 gallon tank, with an average population of about 100,000 small animals, from one to ten million cubic millimeters of sediment is moved each day. Or phrased another way, the entire tank's sediment volume could be completely turned over at least once every three to thirty days. With this amount of jostling and sediment eating, sediment clumping the sediments will simply not occur. Consequently, excess food is eaten and disposed of or recycled as animal or algal flesh, and that the biological filter is maintained in the best of condition. And, best of all you, as the aquarist, didn't have to do anything. The animals did it all for you. All you had to do was to sit back, and enjoy a healthy tank. And, yes, I know it was a dirty job, but somebody had to do it...

As you can see, stirring the tank's sandbed is not only unnecessary, but it would be detrimental, as it will disturb the oxygen gradient needed for the denitrificating bacteria to do their job.

and aanother

he job of the micro fauna is to twofold. First they break down the detritus in the tank into smaller and smaller particles making it easier for the bacteria to utilize, second is to keep the sand bed moving as they dig beneath the surface. This movement is vital to keep the sand from clumping together and to create small currents in the bed bring nutrients to the different zones within the DSB so that the nutrients can be utilized and to move the detritus down through the different zones in the DSB.

As the DSB matures different useful zones form. The two primary zones that are the most useful to use are the aerobic zone and the anaerobic zone. In the aerobic zone, bacteria convert ammonia to nitrites and then into nitrates. The anaerobic zone has bacteria that convert nitrates into nitrogen gas or ammonium, which rise back up through the layers where the nitrogen gas is released and the ammonium becomes food for the aerobic bacteria once again. Also during this process phosphates are released from the detritus and, in a fully functioning DSB, used by the fauna and bacteria as they grow and multiply, thereby cycling the phosphates within the DSB.

More from Craig Bingman
http://www.aquariumfish.com/aquariumfish/detail.aspx?aid=124&cid=124&search=


But there may be other reaosn more in the form of geologic. A low and just right pH in the SB will begin to dissolve CaCO3. If the pH then rises it will then prcip right back out and often right in the same area, causing grains to "clue " together.

 

[angelfish]

thank you Boomer, for all these most useful information

 

[Boomer]

You're Welcome

 

[apollothesun]

ive noticed this is starting to happen in my sandbed. it is sugar size sand, anybody else? should i replace portions of it daily? thanks in advance