A comparison of reciprocating flow versus constant flow in an integrated, gravel bed, aquaponic test system

Abstract

Murray cod, Maccullochella peelii peelii, and Green oak lettuce, Lactuca sativa, were used to test for differences between two aquaponic flood regimes; reciprocal flow (hydroponic bed was periodically flooded) and constant flow (hydroponic bed was constantly flooded), in a freshwater aquaponic test system, where plant nutrients were supplied from fish wastes, while plants stripped nutrients from the wastewater before it was returned to the fish. The Murray cod had FCRs and biomass gains that were statistically identical in both systems. Lettuce yields were good and a significantly greater amount of both biomass and yield occurred in the constant flow treatment. Constant flow treatments exhibited greater pH buffering capacity, required fewer bicarbonate (buffer) additions to control pH and maintained lower conductivity levels than reciprocal flow controls. Water consumption in the two systems was statistically identical. Overall, results suggest that a constant flow flooding regime is as good as, or better than, a reciprocating flooding regime in the aquaponic test system used.

Optimization of Water Circulation Period for the Culture of Goldfish with Spinach in Aquaponic System

“…Nitrite-N concentration also did not show any significant variation but showed slight reduction with increase of water circulation. Lennard and Leonard (2004) in their comparative studies of reciprocating flow versus constant flow in an integrated-gravel bed-aquaponics system showed that constant flow treatment appear to remove more nitrate from culture waters than did reciprocating control treatments, but no significant differences was detected. Nitrate-N concentration of water, which is relatively harmless to fishes, was also found to be in the favourable range in all treatments.…”

Hydroponic systems and water management in aquaponics: a review

“…Increasing the hydroponic surface/fish tank volume ratio from 0.67 to 2.25 augmented the daily water replacement from 1.2% to 4.7% (McMurtry et al, 1997b). Lennard and Leonard (2005) measured an average daily consumption of 2.65% in an AP system with a medium-based hydroponic bed planted with L. sativa for 21 days and observed no influence of the management of the hydroponic section (reciprocating flood/drain cycle vs. constant flow) on the water. Also, the type of hydroponics (gravel, floating or NFT) had no influence on water loss (Lennard and Leonard, 2006) (Table 2).…”

“…In both, the removal of nutrients and/or pollutants is complex and depends on a variety of mechanisms, including sedimentation, filtration, precipitation, volatilisation, adsorption, plant uptake, and various microbial processes (Wießner et al, 2005;Vymazal, 2007;Wu et al, 2014;Barbera et al, 2015;Maucieri et al, 2014Maucieri et al, , 2016. Lennard and Leonard (2005) compared a reciprocating flood/drain cycle (10 min flood every 70 min) to a constant flow in a hydroponic gravel bed (0.52 m 2 ) plated with lettuce during 21-day cycle. They obtained significantly higher lettuce yield (resulting in higher nitrate and phosphate assimilation), better pH buffering and higher dissolved oxygen concentrations in the constant flow.…”

“…In these integrated systems, nutrients that are excreted by the fish or generated by microbial activity (Munguia-Fragozo et al, 2015;Zou et al, 2016a) are absorbed by hydroponically cultured plants, thus treating the water before it is recycled to the fish tank (Endut et al, 2009;Tyson et al, 2011;Nichols and Savidov, 2012;Medina et al, 2016;Nuwansi et al, 2016). AP has received considerable attention due to its capability to sustain water quality, minimise fresh water consumption, and provide a marketable vegetable crop (McMurtry et al, 1997a(McMurtry et al, , 1997bAdler et al, 2000a;Lennard and Leonard, 2005;Graber and Junge, 2009;Danaher et al, 2011Danaher et al, , 2013Pantanella et al, 2011Pantanella et al, , 2015Espinosa Moya et al, 2016;Shete et al, 2016). Nevertheless few microbial studies have been conducted to determine food safety status (Elumalai et al, 2017) suggesting that further research is needed to evaluate this aspect.…”

Adequate Design for Aquaponics with Case Study

“…Many researchers have shown that high PH plants display nutrient deficiencies and on contradiction, low PH ammonia accumulates to toxic levels for fish [10], [11], [12] and [3].…”