Hard block of aragonite sand in fudge?

[bashduo]

Was poking around in the fudge last weekend and ran across a "block" of aragonite sand. It was probably about 6" to 8" long and 4" across. The stuff was VERY hard and took quite a bit of pressure to break it apart. Since then tank pH readings dropped about 0.2 to 0.4 on the electronic pH probe. I recalibrated the probe, which didn't change much.) Oddly enough, chemical pH tests did not show the same drop in pH. Chem ical tests remain pretty constant. Since then, electronic pH readings are starting to climb, but only very slowly. Alk. remains around 3.5 meq/L. The fuge was a new addition to the 2 year old system 5.5 months ago. Using 1mm - 2mm dia. aragonite sand bed in fudge. The sand bed is around 3" deep. I've been hoping the sand bed would help with nitrates, but have yet to see any noticable improvements. (Running a calcium reactor to maintain alk and Ca.) Ideas?

 

[Anonymous]

In my experience there are two reasons for a block of sand.

1 - A sand bed without a diversity of sand bed infauna. This allows Bacteria to glue the sand grains together.

2 - A precipitation event.

It's easy to test. Place a piece of the block in a 1:10 clorine-water solution. If the block falls apart then it's bacterial, if it has no effect then it's a precipitation event.

 

[bashduo]

That was pretty much what I was thinking as well. (Lots of pods, but few worms) The chlorine test is a good idea. Thanks

 

[greenman]

Do you have a sand bed in the display? I ask because if you do and its not a clump then I would say that its

" 1 - A sand bed without a diversity of sand bed infauna. This allows Bacteria to glue the sand grains together. "

"The fuge was a new addition to the 2 year old system 5.5 months ago"

 

[bashduo]

Main display with a 1" - 2" coarse crushed coral bottom. To help "mature" the refugium "sand" bed, I've moved a couple cups of the 2 year-old display substrate (with worms, etc. down to the refugium). Also, slowly (only a couple cups / week - don't want to bury existing substrate too quickly) adding aragonite sand to the main tank bottom. - Not much, but enough to add a nice 1" - 1.5" layer to the bottom. Hoping it help with the stability of the system and give a nice layer fo sand sifting critters. (The existing old substrate was too course for sifting gobies, sand stars, etc.)