"Export bricks" vs regular rock in low flow area?

[keddre]

Question: What is the difference between the various "export bricks" and just placing live and/or dry rock in a low flow area? Maybe I'm missing something, but my understanding is that these various bricks are just custom made rocks with tunnels all throughout it (porous might be the word I'm looking for).

 

[Brew12]

Question: What is the difference between the various "export bricks" and just placing live and/or dry rock in a low flow area? Maybe I'm missing something, but my understanding is that these various bricks are just custom made rocks with tunnels all throughout it (porous might be the word I'm looking for).

The big difference is uniformity. With a man made brick you have a good idea of its porosity. With rock, you have no idea how porous it is beyond what you can see. The irregular shape of rocks also leads to varying amounts of denitrification.

 

[Lowefx]

The big difference is uniformity. With a man made brick you have a good idea of its porosity. With rock, you have no idea how porous it is beyond what you can see. The irregular shape of rocks also leads to varying amounts of denitrification.

Which then equals more surface area. More surface area is beneficial to denitrfication.

 

[AlexStinson]

Which then equals more surface area. More surface area is beneficial to denitrfication.

'Surface Area' in this context is not exterior surface but all surfaces on which bacteria can populate. Higher porosity generally = Higher surface area

 

[Brew12]

Which then equals more surface area. More surface area is beneficial to denitrfication.

If you take a export brick and put it in a high flow area it won't do any denitrification because it will not establish an anaerobic zone. In this case, it would make a great location for nitrifying bacteria.

'Surface Area' in this context is not exterior surface but all surfaces on which bacteria can populate. Higher porosity generally = Higher surface area

This is an excellent way of thinking about it. Which bacteria populate it, and the function they carry out, will be determined by placement in the system.

 

[Lowefx]

'Surface Area' in this context is not exterior surface but all surfaces on which bacteria can populate. Higher porosity generally = Higher surface area

We're on the same page. Exactly my thoughts

 

[AlexStinson]

We're on the same page. Exactly my thoughts

Sorry about that I misread your first point.

 

[saltyfilmfolks]

Yes, uniform surface area. The benifit of the bricks is it becomes a controlled dosing method of sorts
If you notice the nutints dropping too quickly you can pull a brick

I'll disagree on the non anerobic zones in higher flow. The bacteria clog the pores inside.

In many sixes full NPS full time feed systems crushed coral is used in a dsb. The nutrient levels are maintained with carbon dosing.

A combination of these two has also been done by hobbyists successfully.
Some utilizing a reverse undergravel system.
One Member here used RUGF with the gravel (crushed coral) in three trays so he could remove one or two if needed.