Backyard Aquaponics
A place to discuss aquaponics

janet, it may be that your bacteria population is large enough to process your 50g/day, but there is more 'room' for bacteria...just that you would have to up your feed for long enough to allow the population to respond and build up. I think if you fed at 25g/day for a couple of weeks, then suddenly went back to 50, you would still see a spike.

You may well be at your max though. Just a thought.

Fluidized bed filters are REALLY efficient at taking care of the Ammonia->Nitrate cycle without taking up much physical space. I've got one on my 75 gallon cichlid aquarium in my family room that's rated for 300 gallons and it's just hanging off the back of the tank.

The 900 gallon version* is 6" long x 3" wide x 35" high.
*http://www.aquariumguys.com/fluidizedbed3.html

Add to that the fact that you can chain these together and you could handle a HUGE amount of biological filtration in a really small space. They're also relatively cheap.

Doing that would mean that the grow beds would only have to be sized to actually house the appropriate number of plants to remove the nitrates.

Thats what I like to hear!

1 mm sand has a surface to volume ratio of 3141:1 So that means I could process 37 grams of ammonia per day using about 16 gallons of sand or a 49 inch tall 10" pipe. That is assuming 1 square meter of surface area can process .2 g of ammonia per day.

I have been studying this for many hours now
However, I think I can design it to always be simple to start and not require a large or powerful pump and also to overcome the problems with power failure; even with 16 gallons of sand. When I get a test model made I will post pictures here.

I am still considering using a 55 gallon of 'bio bale made from shreded cello which is also used in food wrapings.
That is a 50 pound bale and also would be able to process the ammonia. Its 19" x 16" x 40"

My FBF requires very little water flow. I've got a cheap little pump in the tank and I have to dial the adjustment knob on the FBF all the way down to nearly nothing to keep the sand at the right level.

I'm talking about 16 gallons of sand though. I have no idea how much pump would be required for that much sand in a standard FBF. Either way I still love the idea! It does not stink at all

FBF - sounds cool! Do you have to get a pump to operate it, or does a pump come built in? That might help solve my nitrite problem.

They don't come with a pump (at least none that I've seen). They have multiple connectors for different configurations. When they're just hung on the back of a tank, there are 2 connectors at the top. The one connects to a tube that you connect to a small, underwater pump. The other is the return sprayer, which could instead be connected to another hose if you want to redirect the return flow somewhere else.

Since running FBF's on my aquariums, unless a huge increase in ammonia hits from dumping in a bunch of new fish (enough to trigger the white cloud of bacterial growth), I get no detectable ammonia or nitrite in the tanks). It's just nitrAte and that steadily climbs in my standard aquariums.

The sand that comes with the FBF that I linked to is extremely fine. I don't know the exact diameter of the grains, but it's some really small stuff. More like really fine sugar than most beach sand.

I've heard of municipal aquariums or pet stores running one big 30-50 gallon FBF for literally 10's of thousands of gallons of freshwater fish to take care of the ammonia cycle.

oooooo. Must have FBF. :drunk:

As there seems to be some discussion concerning Fluidised Bed filters I thought I'd post this DIY link.....

Has photos and explanations .... DIY Fluidised Bed Filter

If the sand is fine enough then it can have a 10,000:1 ratio surface area to volume! Janet I think that would solve your ammonia/nitrite spike problems once and for all. And it would be very simple and small. I mean 16 gallons of sand to process 1 kg daily feedings! Thats not even the fine sand. Now the question is how many plants is it going to take to remove all those nitrates?

I must have a sure removal or nitrates for this small indoor system so sand looks like the most reasonable option. Its still considered pretty new technology and an improvement to old sand filters and runs circles around anything! The sand self cleans and adjust to any ammonia load. Because there will be periods of time where I must operate completely indoors I don't see a better option for size! I imagine a little 75 gallon gravel pre-filter with about 500 vine plants coming out of it LOL OH! the organic matter does not stick in the filters either so all the nutrient benefits you get from having unfiltered input to your bed are still there!

The only thing that concerns me is if power fails for long it can go anaerobic fast and produce deadly hydrogen sulfide.. However, they say an air stone in the bottom could prevent that and the bacteria do function better with more oxygen. However, from what I understand the sand can stick together if power is lost so you need a strong purge to get it going. None of this is a problem with a small aquarium.

Good link Rupert! Its that simple.

It would also be easy to calculate how much sand you need(if using 1mm sand). At the local equipment rental place they sell sand blasting sand for $8 a 50 pound sack. They have 3 sizes to choose from. The guy at the counter said the smallest is more like baking powder than sand.

Reptile calci-sand is very fine (like egg timer sand) and almost pure calcium carbonate so you might not need any sea shells

FBF`s are mainly for biological filtration so probably still need a mechanical filter/gravel growbed to deal with the solids.

This is what I had in mind. The sand stays to the side so there is never much sand above the inlet so it will be easy to restart if power fails. This way all of the sand is circulated but makes always easy to restart. Perhaps a small inverted cone would work to keep the sand from flowing down the pipe and clogging it.

I agree. I was going to use my out door beds as a pre filter during warm weather and a 75 gallon gravel bed indoors during winter as a pre-filter. That should handle solids. Well, along with some worms it should... I still don't know what kind of worms work best earth worm, red wigglers, or something else..