Anyone Experienced with fluidized bed filter?

I experimented with fluidized bed filters on a few tanks...all planted and lightly stocked; a 20 long, 30 long and 125 gal.

They worked but were somewhat of a pain at times. If the flow through the chamber stopped for even a short time, the sand grains fell to the bottom and impacted, forcing me to shake the chamber when pressure was restored to get the flow going through the chamber and get
the grains suspended again.

Not sure how much biofiltration they actually accomplished as the bioload on the tanks was light and the wide distribution of bacteria on the tank surfaces themselves may have been doing the lion's share of nitrification.

I'm having a hard time envisioning a sump-based FBF in the 10 to 15 gallon range. The key to these filters is keeping the grains suspended in the water column...too little flow from beneath and the grains settle...too much flow and the grains leave the chamber.

In a 10 to 15 gallon chamber, I'd go with lava rock, ceramic rings or some other large-surface-area media that will give you adequate surface area and contact time for your tank.

Mark

I researched them at some point in the last two years. I have a 125g where I am trying to build a perfectly balanced tank between plants, fish, and microscopic guys.

Everything I read about the FSB said it had tons of surface area and was great in every regard (no mentions of maintenance difficulties or ease of use).

I found that they recreated sand agitation that happens in nature where the bacteria like to live. I have play sand in my tank. I introduced trumpet snails to naturally agitate the sand bed. I also introduced blackworms for some agitation. Interestingly, the fish move more of the sand looking for worms than the worms do. I did not take specific measurements before and after introducing snails and worms. I tend to tinker all the time and wouldn't know what to attribute just to this one change.

At any rate, if you have a well balanced 45g sump, more bio filtration may not even be necessary.

Please tell us more about the tank. Who lives in it? What is the water quality like? How quickly does it go bad?

Nate

I have had great tanks running for years, too. I understand mixing it up. For the last few years (since 2012 or so) I have been trying to recreate a perfectly balanced tank relying exclusively on the food chain to maintain my water quality so all I would have to do is add new water every week. I don't want auto water changes but actual balanced water.

I am working toward this with far more bio filter media than would ever be inhabited (it sounds like you may have a similar setup there with a 45g sump). I am now growing plant mass to absorb the ammonia before it processes the rest of the way through the nitrogen cycle. I have worms and snails to grab what food gets lost. I cheat a little and I do fish out all the uprooted plants every few days to reduce floating detritus. The water quality is consistently very good but not perfect as it still requires water changes.

You could do a separate 55g heavily planted tank as a secondary filter for the big one. The fish fertilize the plants in the other tank and the other tank cleans your water.

Good luck on the next part of your quest.

Pinkey, while it is your ultimate goal to never needing to do water changes at all, I would advise against it. You won't have the room for a complete self sustaining closed eco system. You still feed, right? If you feed you, you have to take out nutrients one way or another. Your way of "cheating" does take out nutrients by removing old plant matter - it also takes out accumulated waste products.

For all the parameters you can measure or test against, you can get close to perfect (only needing to feed, export nutrients by pruning plants, and top of lost water due to condensation). It is all those unknowns you cannot (reasonably) test against that make water changes beneficial - maybe only every few months or once a year.

Those are all very good points and if the tank works as well as you describe I will count it a success.

Pinkey said:

Those are all very good points and if the tank works as well as you describe I will count it a success.

Click to expand...

I only ever heard about SW tanks working without ever changing the water other than top off with fresh water and scraping the salt back in tank. Not sure if it is possible with FW.

Ducky, if it is possible I'll find out. It may take me 20 years but I'll do it.