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Evaluation of different hydroponic media

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  • Evaluation of different hydroponic media

    Hi! After dedicating almost the whole weekend to read Dr. Olivier's excellent working paper, y stumbled upon this research on the merits of growth media:

    The authors compared crushed stone (0,5 - 1 cm), river rocks and rafts, regarding fish growth, plant growth, water quality, nutrient removal, and biofilter performance, and reached this conclusion: «The results of all these parameters suggested that the crushed stone medium is the most suitable substrate as compared to river stone and floating raft».

    In this study, the crushed rock is the medium with the smallest particle size and the largest specific surface area. Interestingly, they mention sand (they even cite Dr. McMurtry's work), often equating it to gravel, but didn't use it in their tests:

    «For the hydroponic component, generally sand/gravel/aggregate bed was used (McMurtry et al. 1993; Lennard and Leonard 2004; Endut et al. 2009, 2010; Sikawa and Yakupitiyage 2010; Shete et al. 2013, 2014; Hussain et al. 2014, Hussain et al. 2015; Nuwansi et al. 2015).


    Sand/gravel bed systems act as biofilter, and therefore, it replaces the requirement of conventional biofilters (McMurtry et al. 1997; Seawright et al. 1998; Dontje and Clanton 1999). Also, it acts as a solid filter medium (McMurtry et al. 1997; Seawright et al. 1998)»

  • #2
    It's probably fair to say that of the available options, fine gravel is the more effective media when it comes to mechanical and biological filtration.

    Sand, of course, is better than all of them.

    Why researchers fail to take the investigation one step further (to include sand) is utterly beyond me.