Flood/drain versus submerged biofilters. Which is better?

I’ve seen several aquaponics setups that utilise the flood/drain method to water the plants, and hence act as the filtration for the fishes. I had always wondered whether there is enough filtration of the water for the health of the fish especially when the water runs only 4x per day.

This is why my DIY (do-it-yourself) backyard set up is a continuous flow method (nutrient film technique) utilising a submerged biofilter to filter the fishes’ wastes. I thought it’d be better for the fish to be in a proper aquaculture setup and then have the plants as an accessory. See Facebook fanpage link here.

This paper details the work done to come up with the conclusions that:

1. Removal of organic nitrogen and ammonia was higher in flood/drain biofilters.
2. Removal of nitrites and nitrates was better in submerged biofilters
3. The use of combined flood/drain and submerged biofilters may offer the best solution to the treatment of aquaculture waste.

Having said this, I’d like to do some water quality testing of my own for those with the flood/drain design, to look at TAN and nitrite levels.

Aquacultural Engineering
Volume 50, Number 2 (September 2012)
	Nitrogen removal and changes to microbial communities in model flood/drain and submerged biofilters treating aquaculture wastewater
	Authors:	Simon P. Gregory 1, Paul J. Dyson 2, David Fletcher 3, Philip Gatland 4, Robin J. Shields 1
	Author Affiliations:	1: Centre for Sustainable Aquatic Research, College of Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK  2: Institute of Life Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK  3: RAS Aquaculture Research Ltd, Pen Lon, Maes y Llan, Llandwrog, Gwynedd, UK  4: 31 Spindlewood, Brough, East Elloughton, HU15 1LL, UK
	Source:	Aquacultural Engineering, Volume 50, Number 2 (September 2012)
	Page Numbers:	37 – 45
	Available Full Text:	Full Text: Subscription Required to view full text Format: PDF Size: Unknown Location: Publisher’s Site Authentication: Publisher’s Site
	Abstract:	? Flood/drain biofilters were compared to submerged biofilters for the treatment of marine aquaculture wastewater. ? Analysis of 16s rRNA and amoAgenes by T-RFLP revealed distinct bacterial communities in the submerged and flood/drain biofilters. ? Removal of organic nitrogen and ammonia was higher in flood/drain biofilters. Removal of nitrites and nitrates was better in submerged biofilters. ? The use of combined flood/drain and submerged biofilters may offer the best solution to the treatment of aquaculture waste.
	Citation:	Simon P. Gregory, Paul J. Dyson, David Fletcher, Philip Gatland, Robin J. Shields . Nitrogen removal and changes to microbial communities in model flood/drain and submerged biofilters treating aquaculture wastewater. Aquacultural Engineering, Volume 50, Number 2 (September 2012), pp. 37-45, <http://ejournals.ebsco.com/direct.asp?ArticleID=41AF998AA0FB9C7061FB&gt;
	URL:	http://ejournals.ebsco.com/direct.asp?ArticleID=41AF998AA0FB9C7061FB