Need Bio-filter with LS?

[bkc978]

Hi, i am replacing my 3" CC substrate in my 45G tank (36x12x24H) with 30# aragonite and then 10# LS on top of that. I figure this will give me about a 2" sand bed. I plan on adding 25# of LR in about a month, then adding more until I am happy with the look, and then stocking my tank. (may tank has been running for about 12 months with just a cleaner crew and 1 fish - don't ask)
I know a lot of people have different opinions on sand bed depths - but that is not my question here, I am going with 2" for now.
My question is, when I have the LS and 2" bed in place, should I remocve the biological filtration from my fluval 304 and replace it with carbon? Do I not need the bio filter section when I get the sandbed?
(I also have seeaclone skimmer and 9W UV- I am leaving them in place. No refug)

 

[sly]

I would keep the bio-wheel unless you get a trickle filter... then you can get rid of it.
A sandbed is not very efficient at housing aerobic bacteria but it can support it to an extent. Aerobic bacteria grow much better on a bio-wheel or a trickle filter. It is aerobic bacteria that converts ammonia into nitrite and nitrite into nitrate.
A DSB is good for maintaining anaerobic bacteria. This bacteria goes further down the nitrogen cycle to convert nitrate into free nitrogen gas.

 

[bkc978]

Oh, OK, I didn;t realize it was only DSB that broke nitrates down, maybe I will go with a 5" bed then - that would be enough, right?