Sand or Crushed Coral

[blrrobinson21]

Hello all,
I received my tank from a buddy that has had it up and running for a few years. We made the transition to my house and I have had it for about 3 weeks now. He is old school therefore he had a gravel bed filter in it and is still in the tank now using crushed coral. Im also using two power filters made by tetra but dont know much about them. I read somewhere that the coral bed can cause high nitrates which I have, over 150. I was curious as to if I need or could switch it out for sand and if so how to do it.

 

[Wy Renegade]

Hello all,
I received my tank from a buddy that has had it up and running for a few years. We made the transition to my house and I have had it for about 3 weeks now. He is old school therefore he had a gravel bed filter in it and is still in the tank now using crushed coral. Im also using two power filters made by tetra but dont know much about them. I read somewhere that the coral bed can cause high nitrates which I have, over 150. I was curious as to if I need or could switch it out for sand and if so how to do it.

You can, question is do you want to. To do it right, you basically need to tear the entire system back down again. If you just recently moved it, you're probably having nitrate issues as a result of the move. You have several options; complete removal and replacement (just as well replace undergravel filter as well, unless you are considering a DSB), mixing (which IMO looks like crap) and the CC tends to migrate to the top anyway, and cover the undergravel filter and CC with a fiberglass mesh and layer sand to create a DSB. Just depends on how much money you want to spend and how much work you want to do.

CC beds do work, they just have to be gravel vac-ed on a regular basic to remove organic material. Did you rinse all the CC before replacing it in the tank?

 

[melosu58]

Sand would be better but as mentioned earlier it will be some work to change but it can be done. The problem with CC is that it`s so heavy it will trap food and fish waste under causing nitrates in your tank. Many people have siphoned the CC up and replaced with sand by doing it in quarters. As I said siphon CC up and replace with sand by using a PVC pipe and let it slide down the pipe to the bottom to minimize the sandstorm. Also as mentioned above you could keep the CC but you really need to vacuum it pretty regularly.

 

[blrrobinson21]

Well siphoning and replacing was kind of what I was thinking about. Here's my next question. Would it be ok to leave the bed filter in place and put a 2 or 3 inch sand bed on top of it leaving CC under it?. That would leave about a inch or less of CC. I cant actually use the bed filter with sand can I?

 

[Wy Renegade]

Well siphoning and replacing was kind of what I was thinking about. Here's my next question. Would it be ok to leave the bed filter in place and put a 2 or 3 inch sand bed on top of it leaving CC under it?. That would leave about a inch or less of CC. I cant actually use the bed filter with sand can I?

I wouldn't place sand on top of the undergravel filter. What I would do is leave the CC under the undergravel and a little over, so you end up with a 1 1/2 to 2" deep layer of CC. Then covered that layer with fine black fiberglass mesh (available at your local hardware store). The mesh serves two purposes, one it prevents sand-dwelling organisms and sandgrains penetrating into the lowest level of your DSB; since this in an anaerobic area, you don't want those creatures in there, and you want to maintain the pockets for gas exchange. And two, it prevents the courser CC from working its way to the top of the sandbed. Additionally, because this anaerobic area is acidic, the CC will break down over time adding calcium to your water which will be beneficial for coral growth.

Over the top of the black mesh place a 1 1/2" to 2" layer of courser sand (still the fine sand), but the courser grade. then layer a 1/2 to 2" layer of fine sand on top (I have used both the bagged live sand - which really only supplies bacteria, and dry sand which is then "seeded" with a couple pounds of real live sand aquired online or from your LFS.

As far as the deep sand bed, it will have to be maintained; which you do by buying the proper creatures to maintain it. NO sandsifting gobies or sea stars (as they consume the beneficial microorganisms that are contained in the sandbed). Once established, the DSB must remain undisturbed, as it will build toxic conditions in the deeper anaerobic layers, and disturbing this layer can crash your tank. So after you put down the CC layer and the black mesh, place your LR directly on the mesh; burrowing fish will not be able to get below the mesh to topple your rockwork, and the CC will cushion the bottom glass from the LR. Never vaccum or stir a DSB, except very lightly across the top if needed.

 

[blrrobinson21]

Thats what Ill do then. One last question, whats the differences in a dsb vs a regular sand bed in inches. Is the only reason you dont want sandshifters in a DSB because of bad gasses that can form due to the xtra depth?

 

[Wy Renegade]

Thats what Ill do then. One last question, whats the differences in a dsb vs a regular sand bed in inches. Is the only reason you dont want sandshifters in a DSB because of bad gasses that can form due to the xtra depth?

Shallow sand beds are generally recognized as between a surface layer to 1 1/2" deep (many recommend not going over 3/4 inch). DSB are anywhere from 2 1/2 to 6" deep. The area between is usually referred to as a danger zone, too shallow for anaerobic bacteria to establish, yet deep enough that lots of organics are being trapped and polluting the tank. The main reason for no sandsifters, is because sandsifting fish and stars feed on the living microfauna contained in the sandbed. These microfauna are important for maintaining the integrity of the DSB and preventing the over accumulation and release of toxic gases. In a tank that is too small, sandsifters will consume all the microfauna and thus prevent the maintance of the DSB. HTH

 

[blrrobinson21]

Let me ask you guys this. If I was to pull the lr and fish out of the tank, drain half the water saving it in buckets and then taking out all of the CC and bed filter to replace with dry sand and then but back the rock and water, would that cause another cycle in the tank?

 

[melosu58]

How Sandbeds REALLY Work by Ronald L. Shimek, Ph.D. - Reefkeeping.com

 

[blrrobinson21]

That was a good read with lots of good info thank you. Unfortunately I still didn't figure out if replacing all CC with new dried sand would cause another cycle in my tank. "its probably in the reading I just missed it" It seems like a DSP with the right cuc is the way to go though.

 

[melosu58]

If it was me I would siphon up the CC in quarters and replace with sand. You`ll have limited problems that way. When you replace the sand each time use a piece of PVC and guide the wet rinsed out sand to the spot it needs to go. That`s the way many of us have gone.

 

[colematthewmalaka]

What kind of fish do you have if it's african cichlids it helps to keep the water at the right alkalinity.

 

[blrrobinson21]

No cichlids, Naso tang yellow tangs, tomato clown and bicolored angel.
If I did it in quarters I wouldnt be able to remove the undergravel bed filter, is it ok to leave it?

 

[melosu58]

Yeah I forgot about that. Are you using the undergravel?

 

[blrrobinson21]

Actually Im not using the under gravel at all right now and I know as soon as I put sand in I cant use it. Thats why I didnt know if it would be ok to take out the CC up to the top of the under gravel filter plates, leave the plates in the tank with CC under them and then put the sand 1.5" to 2" on top? And If I can do that do I still do it in quarters or all at once?

 

[melosu58]

The only problem is that if you leave the CC in the sand will find away to move down and the CC will come up on top. Maybe your best bet would be to move it all and remove the undergravel system.

 

[intimatecple]

I would do it as you planned....you will probably go through a mini cycle....but you will have what you want in the end!! IMO