A "bubble curtain" installed on part of South Australia's coast in a bid to prevent giant cuttlefish from the algal bloom has been tested but is not yet operational, as authorities confirm the algal bloom is "persisting" around the state.

The government's weekly algal bloom update revealed rising algal levels at 32 of the 83 testing sites, while the levels remain steady at a further 34 sites.

Decreases were reported at the remaining 17 sites.

The government also defended its public health advice to people with asthma , but acknowledged the information could have had a greater presence on social media.

Deputy Premier Susan Close said the bubble curtain at Point Lowly , on the Upper Spencer Gulf, had now been tested, but had not yet been turned on "because the algae isn't there yet".

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