Table 1. Salt and species-dependent concentration thresholds (in mM, except for the BG11 medium) above which irreversible blooms form.

	BG11	NaNO3	NaCl	KCl	CaCl2	MgCl2
Microcystis aeruginosa PCC 7005	4 ± 1	60 ± 5	60 ± 5	60 ± 5	20 ± 5	20 ± 5
Microcystis aeruginosa PCC 7806	14 ± 1	350 ± 50	350 ± 50	400 ± 50	65 ± 5	55 ± 5
Synechocystis sp. PCC 6803	-	-	-	-	5 ± 1	45 ± 1

Reference concentration of 1 is that of BG11 specified in Material and Methods. The reported concentrations of BG11 are the final relative values while the concentrations of all other salt are the amount added to the samples and are expressed in mM. For comparison, the BG11 at 1X contains 17.65 mM NaNO₃, ∼ 18 mM Na⁺, ∼ 0.2 mM K⁺, ∼ 0.25 mM Ca²⁺ and ∼ 0.3 mM Mg²⁺