sand bed

i have a shallow sand bed in my display, i have around 4" of sand in my refugium, is that enough or should i get it to around 5"? the size of the fuge is around 18 gal.

 

I figure "Oh, what the heck? It's the fuge. Go for 5."

 

I would not suggest it , ive often preached deep sand beds but as the tank ages ( and the sand bed to ) it tends to "hold waste deep down" / leaching nitrates over time .
I would think an even 4 would be pleanty in a 120 gallon, make sure you have a good tank cleaning crew including some burrowing snails , to help keep the sand clean.
I even have 2 sand sifting stars in mine , they do a good job of burowing and turning the sand over ( but keep in mind they dont go down 4 inches )
so any thing below that , may just accumlate over time , thereby leaching nitrates later as the tank grows older.

 

this is in the fuge, i have around 2-4 in in the display

 

Oh im sorry, I guess it would be fine to add' another inch but you do have 4 thus far.
I guess you want pods and such to propagate , and maybe adding some manggrove in there as well .
wouldint hurt to make it an even 5 or so in the fuge

 

yeah that will be after i have my sand bed in, should i leave it at 4 or should i get it up higher? my tank is around 13 in high

 

Only place for a DSB is the refugium as I told the Great one long ago everything as we know it is a Carbon based life form and when we intake sugar carbons as a food source we leave a carbon waste.. And thats why nature made plants to up take our waste carbons as food. Now a DSB can't totally do this job as advertised as there is nothing about 4,000 ft that can ingest Carbon waste as a food source the end of the line waste are methanes and nitrates and sulphide's..

About 15 yrs ago they discovered animals that could use these as a food source totally. All we have is to do this job is Plants that up take these as food.

A DSB will always fill up at some point as will a Plenum But with a plenum there are ways to get around the bio sludge build up.

A DSB will help reduce nitrates but not totally as the new guys all though when the DSBs made a comeback a decade ago.. And on average they all start to fade at about 24 months the algae start to appear.

But when DSB is applied with in a refugium then you have a total system in that the sand bed is safe from predation of the sand fauna and the water moves very slow to allow the DSB to do its job and the plants will send roots into the sand and keep it form clumping and uptake the carbon waste ..Just like fertilizer on a lawn ..

I'd put me 4 inches of sand over a 2. base of dry kitty litter The cheap Ga. Clay unscented kitty litter and then 4 inches of a good aragonite on top and some Caulerpa that send out a root system and not a tumble weed like cheado . If you are going to run a refugium might as well get all the benefits they are capable of performing for you. But you could not pay me to put a DSB in my main tank..

But after saying all of this I'd not add any new sand over what you have if you have 4 inches I'd let it go then as the sand goes in to dissolution over time assuming you used a good grade of aragonite that will dissolve then you can replace that a little at a time not an entire nwe top cap of sand is never a good idea.

 

well maybe ill try that, i have around 4 in and dont want to get another 40 lb to put in there so i might clean it up once in a while. i need some chaeto and caulepora maybe some mangrove what else should i put down there?