fluidized bed filter (and other similar filters)

[rnocera]

I see how many people love fluidized bed filters, and I have a couple questions about them-

What is the standard rule of thumb for how much sand you need in an FBF compared to how big of a tank you have?

Also, the big problem I see with FBFs is that so many people have problems with sand flowing back into the tank, or getting the filter restarted when there's a power outage. I was wondering if there are any other materials that work over using sand. I'm talking about something small for a tank of around 100 gallons. A friend and I have been talking about trying to build something, but using lava rock, or some material manufactured as a biological media. I'm thinking that doing this and injecting air into the input (via an air pump, or a venturi system) would be far more effective in biological filtration than a canister, and at least close to the efficiency of a FBF. Does this make sense to anyone else? Any idea on how it would work?

 

[mrunlucky07]

What is the standard rule of thumb for how much sand you need in an FBF compared to how big of a tank you have?

Roughly 1 lb per 100gallons.

Also, the big problem I see with FBFs is that so many people have problems with sand flowing back into the tank, or getting the filter restarted when there's a power outage.

I have several models on several tanks. I had some aggravation at first while learning how to set them up, however I have never had a restart problem or sand come out once I figured them out. If you set them up like a canister where the top of the fbf is below where the water is coming from the water will not drain out of the fbf and it will start right back up even without a check valve.

A friend and I have been talking about trying to build something, but using lava rock, or some material manufactured as a biological media.

Anything that will bounce around will work, sand has very little unused space between the grains when fluidized so its very effective. Air fluidizees neutral to floating medias. It is one of the best and most popular koi filters where bioload is huge. Fill a barrel full of kaldness media with an air diffuser on the bottom, sery simple and effective.