How long should it take to establish a biofilter....

saltyhog · Aug 15, 2017

I am quarantining two medium sized fish with CP which precludes the use of ceramic media or rock. I observed them for a month in a cycled QT and transferred them to a 20 long 3 days ago.

I had three filter sponges (the ones that fit a 70 gal Aqua Clear HOB filter) that had been in the sump of my DT for 3 weeks. I put them in the HOB of the 20L and added ammonia up to 1.5 and it took 2 1/2 weeks for the ammonia to go down to zero. After a few more days I did a complete water change and transferred the fish to the tank. 48 hours later I already had a small amount of ammonia in the tank, and this is with very modest feeding. Thankfully CP is ok to be used with Amquel and other ammonia detoxifiers or I would be in a quandary.

How long to obtain and how vigorous a biofilter are you able get with seeded filter sponges alone?

Brew12 · Aug 15, 2017

saltyhog said:
I am quarantining two medium sized fish with CP which precludes the use of ceramic media or rock. I observed them for a month in a cycled QT and transferred them to a 20 long 3 days ago.

I had three filter sponges (the ones that fit a 70 gal Aqua Clear HOB filter) that had been in the sump of my DT for 3 weeks. I put them in the HOB of the 20L and added ammonia up to 1.5 and it took 2 1/2 weeks for the ammonia to go down to zero. After a few more days I did a complete water change and transferred the fish to the tank. 48 hours later I already had a small amount of ammonia in the tank, and this is with very modest feeding. Thankfully CP is ok to be used with Amquel and other ammonia detoxifiers or I would be in a quandary.

How long to obtain and how vigorous a biofilter are you able get with seeded filter sponges alone?

I've had great luck with them even while treating small tangs in copper.

I find that most people who have problems with sponges seeded in their sump is that they don't get enough flow through them. Just putting them in your sump isn't enough. If water isn't flowing through the sponge then it isn't getting well seeded. I don't have a great way to do this which is why I normally just use Biospira a few days before adding fish. I've made it work well by jamming a layer of them between my fuge and return section but it isn't convenient.