Sand clumping in high flow area ..why?

[BlackTip]

I used Arag-Alive special grade sand. I dose through a doser once every 2 hours at the slowest rate possible (5ml min.). Soda ash is dosed on an even hour, and calcium on an odd hour. So, there is one hour between dosing. The doser drops the liquid in between two baffles close to the return section. It is high flow area, because there is the UV return placed there at 350gph.

I noticed that the area under the return pipe in the DT (I have two returns pipes) is clumped solid. Also, there are some clumps under the rocks. I have some small rocks with frags that were placed on the sand bed.

Any idea, why it is happening?

Thanks,

[outy]

Bacteria populations.

My whole DSB is almost solidified after 6 years.

[BlackTip]

Bacteria populations.

My whole DSB is almost solidified after 6 years.

Do you mean high bacteria population?
Is this good or bad?

The sand in the open sand areas are loose, and I vacuum it regularly.

[bertoni]

The solidification likely would prevent the DSB from doing much filtration due to the loss of surface area. Bacterial growth is one possible cause of solidification. I'm not exactly sure what's happening, though.

[outy]

Is this good or bad?

.


Well you don't want it clumping, and it needs to be manually broken up.

I can only get to about 5% of my sand because of coral growth.

Bad? it is as bertoni explained.

Good? I don't think it is.



I have no idea why it happens either 25 years in this hobby, and multiple times. I change DSB every 5 - 10 years to fix it

[BlackTip]

Thanks guys.