MgNH(4)PO(4)center dot 6H(2)O (struvite) was crystd. from dild. aq. solns. NH(4)H(2)PO(4) in presence of sea water as Mg source in a continuous draft tube crystallizer with mixed suspension mixed product removal under size-independent growth conditions at PO(4)(3-):Mg(2+):NH(4)(+) = 1:1.2:1, 298 K and pH 9 for 900 s. The product contained mainly struvite (90% by mass) and Ca(5)(PO(4))(3)OH (hydroxyapatite). The crystal nucleation and linear growth rates of struvite were detd. (3.4-21).10(8) 1/(s.m(3)) and (9.85 +/- 0.25).10(-9) m/s, resp.) from the product crystal size distribution. The agglomeration and attrition effects as well as significant diversification in the struvite crystal habit were also obsd.