Crashing Nannochloropsis Culture

[Koonitdo]

Hi all,

I realise that my nannochloropsis culture keep turning yellowish everytime i split a dense culture. i believe it will crash in the next 2 days. what have i done wrong?

i had used 1/3 of dense culture with 2/3 new clean seawater. added 1ml of f/2 for every new liter of seawater. i had sterilize the container as well as the new seawater by microwaving them for 3 mins. lighting is provided 16hrs and 8 hrs darkness. culture is placed under shelter away from the heat as well.

can anyone point out my mistake? or advise how to correctly split my cultures?

thanks in advance!

picture attached is after 24 hrs from split. a yellowish color was observed. the second picture is more severe

[FuEl]

How did you prepare the new seawater?

[Koonitdo]

How did you prepare the new seawater?

The Seawater is filtered thru a 5 micron sieve, and microwaved for 3 mins.

i always have this problem when i split my culture.

it would start to grow denser when i combine 2 failed culture together. i was wondering if it is due to the lack of f/2? bawater was suggesting 1ml of f/2 for every liter of sea water. i drip only 1.45ml of f/2 per 3.78L of seawater.

[FuEl]

Maybe diluted too much? Try 50% new water and 50% stock culture.

Or another possibility is splitting too soon?

[Koonitdo]

i went to drip more f/2 into the water and it seems to be getting better but very very slowly. some other possible causes i could think of is that i did not dechlorine my tap water when i was diluting the seawater to achieve 1.020 in salinity.

the density was really thick when i split them. maybe i did not split it during the exponential phase of the bloom. but i would try splitting it 50-50 in the future.

algae culture seems so tough ><

[Koonitdo]

manage to revive the algae, but i now worry its the wrong algae coz this batch seem rather hardy.

it has remained at its peak for like a week now and no sign of crashing. i have read online somewhere (tried to revisit the site but couln't find it) that nannochloropsis could mutate into some other cell which are more hardy. Any idea how can i spot if the algae has changed?