shallow sand bed

[beerbaron]

hello all, i have been doing some extensive searching here and on other boards, and here is the deal. i am removing my wet dry, and this will give me more room in my sump/ cabnet to allow me to signifigantly enlarge my refugium which has a 4" dsb. this is my concern. i currently have a 1" crushed coral layer in my main tank. i have read that this is a less than desirable subsrate, and i would like to replace it. i am slightly worried about putting a dsb in the main tank as well, and since i have a large one in my refugium i dont really need one anyways. so down to my real question, what depth of sandbed and material do you recomend in my scenario. i have never really seen anyone talk about using this setup or reccomending it, but in most tanks i see, they have a shallow sand bed. i have also heard that smaller partical sizes have less buffering i dont know how true that is.
comments and suggestions would be appriciated
bb

 

[goldenboy]

since you already have CC as your substrate I would just leave it in there. Theres no sence in disturbing your micro populations by removing it. Since you already have a dsb in your sump I would just add about 3" of sugar fine or small sized (1-3mm) aragonite sand to the exsisting sand in the main tank.

Keep in mind that small grain sand has much more surface area for bacteria to grow unlike your CC which I am assuming consists of large pieces. It is also creates a better invironment for micro worms and other sand dwelling orgnanisms to reproduce in. Also having a dsb is an excelent way to reduce nitrate through the anoxic layers in the lower portions of the sand. HTH

 

[beerbaron]

i realize all the benifits of a dsb. i was wondering if it would be benificial to replace the cc with a shallow sand bed to eliminate trapped detritus. i am not worried about killing the fauna because it will be re seeded by the remote dsb.

 

[goldenboy]

Well if your not worried about losing the fauna then I guess you could go ahead an remove the CC. It just seems like more trouble than it is worth to me, and I don't think that you would have to much trouble with detrtitus getting trapped as long as you have more fine sand than large CC. IMHO a varried size sand bed is a good thing to have anyway because it keeps the sand from getting to compact.

 

[SPC]

Posted by Beerbaron:

i currently have a 1" crushed coral layer in my main tank.
i have read that this is a less than desirable subsrate, and i would like to replace it.

-Good idea, the only thing it is doing is collecting crap.

i am slightly worried about putting a dsb in the main tank as well, and since i have a large one in my refugium i dont really need one anyways.

-That would depend on how large it is as to whether it is going to be functional or not, the more the better.

so down to my real question, what depth of sandbed and material do you recomend in my scenario. i have never really seen anyone talk about using this setup or reccomending it, but in most tanks i see, they have a shallow sand bed.

-Most reefers now have deep sand beds, minumum 4". Use the finest sand (oolithic) that you can. It is also recommended to use aragonite sand because the grains have smooth edges as compared to silica sand which has jagged edges. The silica sand could damage some of the animals that live in the sand, these animals are a very important part of keeping a DSB healthy.

i have also heard that smaller partical sizes have less buffering i dont know how true that is.

-IMO don't worry about the buffering aspects, a very low PH is required for this and a PH this low would cause all to die in the tank anyway.
Steve

 

[olgakurt]

I'd only suggest if you remove the CC, you be careful about dissolved oxygen levels plumeting as you disturb organic material trapped in the bed.


IMO, the intricacies of a sand bed are largely related to micro-environments.

Two points people often don't get are:

1) you can get denitrification (conditions) in less than 1/4" of bed-I've measured it.

2) you can get buffering/Ca without pH affects in the rest of the tank. This occurs in micro environments, the water becomes saturated at the level and diffuses/migrates out. If the overlying water is not already saturated at its current conditions some of that load will remain dissolved and available.

Is is the relative degree and efficiancy of these processes that may be questioned relative to the overall operation of the tank.

I hate the 4" rule espoused on the boards. It's too general and pertains more accurately to relatively sterile sand with no body (organic material).

In general:

the greater the flow the more efficient bed processes will be coupled to the water column.

The slower the flow, the shallower denitrification conditons will occur in the bed and less coupled processes will be with the water column.

The more organic material in the bed, the shallower denitrification conditions occur and low pH conditons will develop.

The smaller the particle size, the greater the surface area for bacterial colonization and mineral dissolution (along with reduced water flow).

silicate WILL dissolve from silicate minerals. Whether that creates problems in a tank probably depends on the relative ratio of other nutrients which is largely beyond your control to the degree necessary in the tank.

ok, enough ranting.
_________________
Spyder Victor

 

[SPC]

Posted by Ogalkurt:

I hate the 4" rule espoused on the boards. It's too general and pertains more accurately to relatively sterile sand with no body (organic material).

Have you discussed this with Dr Ron and Rob Toonen? The reason this is "espounded" on the boards is because that is their recommendation. Now if you feel that they have been "espounding" the wrong information may I suggest that we clear this up with a dialog about the 4" rule with them.
Steve

 

[Anonymous]

Have you discussed this with Dr Ron and Rob Toonen?

I've talked about it with Rob, and I was one of the big participants in the sand bed discussions on [email protected] with Ron when we went over the subject for months. I've also done "down-n-dirty" tanks both ways just to fiddle with sandbed dynamics. When olgakurt says....

1) you can get denitrification (conditions) in less than 1/4" of bed-I've measured it.

2) you can get buffering/Ca without pH affects in the rest of the tank. This occurs in micro environments, the water becomes saturated at the level and diffuses/migrates out. If the overlying water is not already saturated at its current conditions some of that load will remain dissolved and available.

Is is the relative degree and efficiancy of these processes that may be questioned relative to the overall operation of the tank.

....I'm in complete agreement. Do note the rider at the end, though.

 

[SPC]

Is is the relative degree and efficiancy of these processes that may be questioned relative to the overall operation of the tank.

-I agree Charles, so what would you suggest as sound advice for someone asking this question? Have we got some type of formula example: 1 tang = 1/4" of sand? I mean if we are going to "espound" on this topic we need to have some data to go by.
Steve

 

[Anonymous]

As Ron would say, "Damifino." It's not like there's been empiric studies on this, Steve. While the level of knowledge on how sandbeds "work" has come a hell of a long way since 1997, there's still plenty that's guesswork.

If you have an interest, you might dig up Harker's old rebuttal pieces to Ron in Aquarium Frontiers. A number of his references do make for thought provoking reading.

 

[beerbaron]

umm ok well im not really trying to debate or listen to a debate on sand bed depths, i as i stated, already have a dsb in my refugium. good or bad whatever. all i am saying is that i dont want one in my main tank, and if i put a shallow bed in there, will it be better than crushed coral(1/4" pieces) and in what ways, and in what ways is it going to be worse.
some points (not all) that i was sorta expecting to be brought up are:
detritus build up in coarse substrate which would require siphon removal
less buffering and ph influence with smaller substrate
im sure there is more advantages/dis adv. that i dont know about.
i have been under the assumption that cc is an out of date approach, i may be wrong, but i havent seen cc in any tanks ive seen on members websites.

 

[SPC]

Posted by beerbaron:

umm ok well im not really trying to debate or listen to a debate on sand bed depths, i as i stated, already have a dsb in my refugium. good or bad whatever.

- If you haven't noticed before, threads can often go in different directions due to thinking people answering the questions.

all i am saying is that i dont want one in my main tank, and if i put a shallow bed in there, will it be better than crushed coral(1/4" pieces) and in what ways, and in what ways is it going to be worse.

-Yes, that was already pointed out to you by :
Goldenboy:

Keep in mind that small grain sand has much more surface area for bacteria to grow unlike your CC which I am assuming consists of large pieces. It is also creates a better invironment for micro worms and other sand dwelling orgnanisms to reproduce in. Also having a dsb is an excelent way to reduce nitrate through the anoxic layers in the lower portions of the sand. HTH

some points (not all) that i was sorta expecting to be brought up are:
detritus build up in coarse substrate which would require siphon removal

-And I answered that with:
"Good idea, the only thing it is doing is collecting crap".

less buffering and ph influence with smaller substrate

-And I answered that with:
"IMO don't worry about the buffering aspects, a very low PH is required for this and a PH this low would cause all to die in the tank anyway."
And Olgakurt said:
" you can get buffering/Ca without pH affects in the rest of the tank. This occurs in micro environments, the water becomes saturated at the level and diffuses/migrates out. If the overlying water is not already saturated at its current conditions some of that load will remain dissolved and available.
Is is the relative degree and efficiancy of these processes that may be questioned relative to the overall operation of the tank."

im sure there is more advantages/dis adv. that i dont know about.
i have been under the assumption that cc is an out of date approach, i may be wrong, but i havent seen cc in any tanks ive seen on members websites.

-And this was answered by me:
"Most reefers now have deep sand beds, minumum 4". Use the finest sand (oolithic) that you can. It is also recommended to use aragonite sand because the grains have smooth edges as compared to silica sand which has jagged edges. The silica sand could damage some of the animals that live in the sand, these animals are a very important part of keeping a DSB healthy."

So, exactly where did we fail in our attempts to be helpful and answer youe questions?
Steve

 

[beerbaron]

sorry bout that my mind is running a bit slow today and needs to be spoon fed, i did not feel i was being rude though and as i value your opinions i was also looking for somepeople to second these beliefs. my next concern is this:
you stated:
"Most reefers now have deep sand beds, minumum 4". Use the finest sand (oolithic) that you can. It is also recommended to use aragonite sand because the grains have smooth edges as compared to silica sand which has jagged edges. The silica sand could damage...."
i have seen many people trash dsb's in the main tank due to unstability and whatever, im sure you know what i mean. im worried about this, which is why i have one in my sump and refugium which overall takes up the same amount of space as it would in my tank. also, i like the look of a shallow sb better. and while most people may be using dsbs this does not mean it is the best option, as a few years back the majority of people used wet dry filters which now seems to not be the best option. i am just trying to make si get all opinions, not just the majority.

 

[SPC]

Posted by beerbaron:

and while most people may be using dsbs this does not mean it is the best option, as a few years back the majority of people used wet dry filters which now seems to not be the best option. i am just trying to make si get all opinions, not just the majority.

-So then you want to hear from people that do not have a DSB in their main tank, I did not realize that was what you were after.
Steve

 

[beerbaron]

not nessisarily, if you can tell me any downsides of shallow sand beds thats helpful to. do you think i am going in the wrong direction? i gues as long as a ssb is better than cc it dosnt matter

 

[beerbaron]

ok i guess i will just go for it then. im getting some sd sand 2 night.

 

[ReefLion]

Beer,

I have the same set-up you are considering. I see no disadvantage to the shallow sand bed in the display tank. Mine is about an inch think, and is basically there for looks more than anything. It still maintains what appears to be a healthy population of critters to keep it clean. That to me is enough of an improvement over the CC, which probably is trapping detritus.

Tim

 

[rikacarl]

beerbaron,

I have seen many nice tanks set up just like yours. I don't see any problem with having a 1" sand bed in the display tank, why don't you just let it be? Sure it may work better if you had more fine sand instead of CC. But is it really worth the trouble? If you dump 2-3" of fine sand on top of it, you most likely will trap and kill the critters that live in the all ready established shallow portion.

Are you completely breaking down the main tank? (removing all the rock etc.) If you are, then I would say remove the 1" CC and replace it with 1" fine sand. (if that is the look you want) If you are not, I would just let it be. Just IMO I guess...

If I had a large 4"+ DSB seperate from the main tank, I would have 1" or less fine sand in the main tank. 4" of sand really takes up a lot of display space.

 

[beerbaron]

i have heard from many people that with larger dia. substrate you need to siphon the gravel due to the large amount of detritus which collects there. plus from what everyone has been saying, there are no advantages of cc so why keep it? it may be a pain to replace, but it is still "playing with my fish tank" :wink: so it wont be to bad.

 

[Anonymous]

i have heard from many people that with larger dia. substrate you need to siphon the gravel due to the large amount of detritus which collects there. plus from what everyone has been saying, there are no advantages of cc so why keep it? it may be a pain to replace, but it is still "playing with my fish tank" :wink: so it wont be to bad.

siphoning it out is definitely the way to go-plus the water change involed will help offset any system disturbance

mho-i agree with the opinions on cc being not as good-larger grain size always equals larger spaces equals better dirt trap.