Replacing bio-balls with LR

[nsinger]

I have a 90 gal FO that has a wet dry with bio-balls. The nitrates have been very high (aka nitrate factory) and I've decided to transition to LR and make the wet dry area a refugium. Any ideas on what % of bio-balls at a time I should replace with LR and how often? I was thinking of replacing 1/4 of the bio-balls with 20 lb Live Rock a month for 4 months. Thanks.

 

[sjm817]

This months magazine has an article addressing this question.
http://www.reefkeeping.com/issues/2008-06/newbie/index.php

One of the poorer “Help Me” replies I see is when someone asks, “I have a wet/dry and use bioballs. Should I replace the bioballs as I have high nitrates?” The “helper” then tells the person they should replace the bioballs with live rock rubble (small broken up pieces of LR). The bad part is, that doesn’t fix a thing and even may worsen the problem.

Remember when we talked about denitrification, we said that anoxic conditions must be present. In fully submerged live rock, located in the display or sump, the pore structure does provide a limited area for anoxic conditions to form. Now place that same rock in air and just splash oxygenated water over it hour after hour. Anoxic conditions my eye; there is not a low oxygen zone on the rock. Using rubble to replace synthetic media in a wet/dry doesn’t solve a nitrate problem. It may, in fact, make it worse as often cyanobacter will grow on the rubble. Cyano has the ability to “fix” nitrogen, that is, convert nitrogen gas to ammonia or directly to nitrate. With cyano getting all the nitrogen gas it can use with atmospheric exposure, it may well add nitrates into the tank on top of what the tank produces itself.

So, if you are replacing the bio balls with LR, it depends on how you do it.

 

[themadreeferTN]

Ive done it both ways and IMO the biggest problem with either is build up of gunk in the rock or balls.. The advantage to the rock is bacteria may colonize more quickly.

 

[nsinger]

My plan was to do away with the wet dry all together and put the LR in the display and build a refugium in the area where the wet dry had been.

 

[sjm817]

<a href=showthread.php?s=&postid=12710201#post12710201 target=_blank>Originally posted</a> by nsinger
My plan was to do away with the wet dry all together and put the LR in the display and build a refugium in the area where the wet dry had been.

That is a good plan :thumbsup:

 

[snorvich]

I like that plan as well. Be sure your rock is fully cured though.

 

[nsinger]

Thanks. I will make sure that the rock is fully cured before adding it to the tank, since I do have livestock in there now.

 

[seapug]

The concept of bioballs vs. live rock in a trickle filter is a tough one for people to wrap their minds around, so I'm glad to see Waterkeeper covered this topic in his article and even happier to see sjm817 quote it! Worthy of a sticky.