Shell substrate

[manny mandarin]

Dont want to sound like a noddy but could i use just shells as a substrate instead of sand without altering water parameters ie too much calcium, the reason i want to do this is it has a load of nooks and crannies for pods to hide and breed to feed my mandarin

 

[Randy Holmes-Farley Verified Community Expert]

It also has a lot of nooks and crannies for detritus. In my system, I don't care about detritus, but a lot of people do care a lot.


What sort of shells? How big?

There's no concern about boosting calcium excessively.

 

[manny mandarin]

Hermit size with maybe the odd bigger one for decoration I thought it might look better than live rock rumble but do the same job eventually might have to up my cuc as well

 

[Randy Holmes-Farley Verified Community Expert]

Assuming they are well cleaned, there won't be any chemical issue from them dissolving.

I don't think you will have anoxic regions for denitrification the way you do with rock rubble, however.

 

[manny mandarin]

Anoxic??

 

[Randy Holmes-Farley Verified Community Expert]

Low oxygen regions inside of rock pores or deeper in sand beds. It's a place where nitrate can be exported from the tank as N2 gas. I commented on that when you said do the same job as rock rubble, which it may not in that sense. But if you just mean coat the bottom, it will do that.

 

[manny mandarin]

So am i right in saying an anoxic region is beneficial to removing nitrates. My thinking was the shells, when live, will create a large surface area for microlife such as pods to live unmolested