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1234
10/09/2009, 09:15 PM
Sometime ago I was reading thru here and there was a blurb about gravel compacting or clumping like it's starting to melt. I'm no eggspert in chemistry so is my alk too low or high? Or is it the PH?

I remember going one way it was too acidic and the other way ?? Been too long.

Any help would be great.

Current tank: 36" x 24" x 22" = 80 gals with fuge total about 110 gals

PH 8.7 according to Milwaukee controller
ALK 8 Salifert
SG 1.024
PO4 0 Salifert
NO3 0 Salifert

top off w/kalkwasser

Billybeau1
10/09/2009, 10:18 PM
I'm not sure what your question is. First off, I doubt your tanks pH is at 8.7 You may try cleaning and calibrating the probe. They do drift high when dirty.

Second, if you dose limewater, sometimes the area which you dose it in can cause the substrate to clump. Think about what makes concrete. Lime,sand and water. :D

Randy Holmes-Farley
10/10/2009, 06:51 AM
New sand and high pH seem to promote such issues.

There are two different theories about how sand beds solidify, and I am not sure which is correct (perhaps both). Such solidification most often happens in new aquaria.

The first possible explanation is simply that calcium carbonate is precipitating onto the sand grains, cementing them together. That would be promoted by high calcium, alkalinity, and especially pH (the higher it is, the more likely it is, but many sands are fine at pH values up to pH 8.5), and low magnesium. It would also be promoted by a lack of organisms stirring the sand, and a lack of a good coating of organics, phosphate, magnesium, and bacteria on the sand (for example, on new sand).

The second theory is that bacteria growing on the sand cement it together with organic or inorganic materials. Depending on what exactly was being deposited, that would be promoted by a lack of organisms stirring the sand, as well as the same factors above.

Boomer
10/10/2009, 09:04 AM
We know that fresh sand lowers the pH by almost .5 pH with some sands within a few days and brings about he precip of Hi-Magnesium Calcite on the fresh surfaces. There is also "Early Marine Diagenesis" where pore waters cause the dissolution of aragonite and then the recyralization to Magnesium-Calcite.