Southdown sand

[merk1_99]

Ok I need someone to explain to me why Southdown sand is better than say 1-2mm CaribSea argaonite, or 2-5mm aragonite. I understand the pleasing aestically look, and the cheap cost. My feeling with the smaller grain size the sand will compact down more reducing the water's ability to flow around the individual grains. With this in mind I would think that the sand bed would become a nutrient sink, causing nitrates to skyrocket over time. The size of the cleanup crew require to maintanence the Southdown would become enormous I would think. With my 2'' aragonite 2-3mm grain bed I have 30-40 nassarius, 20 cerith, and 2 conchs. A large grain would have the flow and would allow the breakdown of trapped detritus a little easier. I just need to get a handle on this before I set up my new tank. I should add I am not going to have a DSB but rathe a SSB <2'' all around.

 

[Moe_K]

The micro-organisms that convert nitrates to nitrogen gas require an anaerobic environment. I'd want less flow in their zone.
Southdown is nice because it's cheap.

 

[Aquaman_68]

I'm starting to think that southdown should be used in sandboxes only. I'm thinking about siphoning it out little by little & replacing it with carbi sea with a little heavier grain or at least mixing some in with it.

 

[gurumasta]

I'm starting to think that southdown should be used in sandboxes only. I'm thinking about siphoning it out little by little & replacing it with carbi sea with a little heavier grain or at least mixing some in with it.

thats a good idea. i mix 50/50 southdown, carib sea and it works out good. i put the southdown in fist then the caribsea on top. over time the snails and stuff mix it together and high flow doesnt cause such bad sandstorms.

 

[merk1_99]

I'm thinking that I need to mix at least 50/50. I'm just concerned a straight southdown bottom will become a nutrient sink. It is better to pay more for the CaribSea than to face a nitrate epidemic down the road....Of course I have no evidence to support my hypothesis just a feeling. BB is not an option for me as I don't like the look, and I'm sure my dragon goby would be pissed. Plus I truly wonder if BB wouldn't become more problematic in the long run, not including the extra maintanance of siphoning detritus all the time.

 

[zear0]

I don't think the purpose of the sand bed is to have water flowing through it. As Moe_K mentioned, the denitrifying bacteria needs an anaerobic zone to live in.

Southdown is cheap and dead. Hence the need to "seed" it with "live" sand from a mature tank. I guess the aragonite substrates need to be seeded as well, but it will leach calcium into the water which is nice.

I'm regurgitating this from memory of what I read a few months ago...

As particle size increases from grain of sugar size to a certain point (2 or 3mm), it takes a deeper sand bed to do the same job denitrifying. I think this is becuase oxygen and water will penetrate deeper into larger grained substrate. Once you pass much higher than 3mm grain size, the substrate will become more of a detritus trap because water will penetrate even deeper with pollutants in suspension. This is why crushed coral is so "un-recommended"

They also recommended against mixing granularities becuase this will cause the sand to pack down more densely than just going with the smaller sized grain. The larger granules will settle together with the smaller granules crammed into the crevices between the larger.

Some sand sifting critters also may be affected adversely by a larger grain size.

I can't remember which book I read this in for sure... Maybe Calfo and Fenner's "Reef Invertibrates" book?

 

[Moe_K]

Rob Toonen is the substrate king. He went over the different substrates at MACNA 17.
He'll be visiting the BRS in March.

 

[gettes]

I can't remember which book I read this in for sure... Maybe Calfo and Fenner's "Reef Invertibrates" book?[/QUOTE]

I just picked up a copy of that yesterday from Marc down at Fishy Business and read about the DSB's last night. Your memory is right on. I don't really know much being a newb and all, but I have been doing a ton of research and I think I'll be going with a DSB. It seems to me if you want a properly functioning DSB then the small grain size is really the best way to go.