Research: Biofilters Help!!

[Ryan D]

I am graduate student and I will be conducting my thesis research soon with aquaponics. I have been debating with individuals on biofilters. I will have multiple systems running at the same time just fyi. To be brief I will have a 55 gal rearing tank with 5 1lb fish/tank. Grow beds will be roughly 2'x6'x1' media filled hydroponic subsystems and floating raft. (Subsystems will not be connected together, one bed/rearing tank). Each of my trials will last for 60 days, and I will be growing sweet basil. I will be analyzing macro and micro nutrients within each system. The big question is, are biofilters essential for a system of this size and trial period? I know the media filled subsystem should act as a biofilter itself, but the rafts are the problem. I want the least amount of influence as possible pertaining to nutrients/waste for analytical purposes. But for replication, if one subsystem requires a biofilter I will have to use one on the other.

(Sorry for being so ambiguous, the scientific field can be very competitive, do not want to share all experimental details right now. Not doubting the integrity of individuals part of this community, just protective : ) ) Any help will be greatly appreciated. Thanks!

See attached picture for visual comprehension. 

[Todd Sowell]

With a system that small and trials that short I don't know that a filter will have much time to build up any nutrients anyway.

A raft system by definition needs added filtration.

FYI Dr Wilson Lennard got his PhD using aquaponics to grow basil.

[Ryan D]

Thanks Mr. Sowell for replying. I was thinking exactly that. If I was to use a biofilter, they would be cycled for about a month before each trial to increase Nitrosomas and Nictrobacter sp. I value Dr. Lennard and Dr. Rakocy's work so much, excellent research and publications! Thanks again!

[Jonathan Kadish NYC AA Chair]

Yeah, don't forget the Bio part of bio-filter which will get richer over time - it took almost 3 months for algae to finally find my system suitable. Many people say you won't get the best results for 6 months or more so your trials will be indicative of a young system. If you talk to Dr Rakocy and Dr Lennard they will suggest to you what still needs to be researched. One thing Dr Rakocy mentioned was nutritional analysis. They are approachable chaps so you might track them down.

[TCLynx]

Now I know Friendlies has done their micro systems with no additional bio-filter before the rafts but those systems generally have very low stocking densities and sometimes have difficulty with starting up with fish and low nutrient availability early on.

I would definitely think that sizing some sort of bio-filter to make sure that the raft trials have an equal amount of filtration as the media beds would be necessary since if you are simply doing a tank and bed and some have media and some are just raft, you will have the added variable that the raft trials will be under filtered.

[Ryan D]

Thanks Mr. Kadish and Ms. TCLynx for replying. Those all all great ideas! I will run these over with my advisers and see what they have to say lol. If any more ideas pop up, let me know!

[Averan]

maybe do a third system combining the first two systems where you tie in a media bed for bio-filter which then feeds the rafts.  ;)

[TCLynx]

Averan's idea sounds kinda good to me.

What is it exactly that the trials are trying to pinpoint?  If it is the plant's uptake of nutrients in the different growing methods, it may actually be helpful to have both growing methods on the same water supply/system to reduce the number of variables involved.

[Ryan D]

I will be analyzing macro and micro nutrients within the different systems, also I will be using different "nutrient" sources. So I cant really tie the systems together.

[Averan]

just sayin you should consider a third test system that is a combination of the two....you may find surprising results.

A = x

B = y

A+B = xy

[Ryan D]

Hmm I will look and see if I can fit that into my budget.