Crashed phytoplankton culture

[Joseph_Joe]

Hi all,

I was happy to have started my first low cost phytoplankton culture based on tutorials seen on YouTube.
It was a half gallon jar with a starter culture, fertilizer, and saltwater.
I set the jar in my balcony with air flowing in from an airpump.
Culture was getting darker every day which is a good indication.
Today was the 8th day and I was about to harvest it as soon as I get home but I found that the culture went white (pic below).
All I know is that today was a hot day (36°C) but even few days ago it was 34°C but nothing happened.
Jar was fully exposed to sun from 1 PM up to 6 PM based on my appartement exposure.

What could have happened ? Did the hot weather + direct strong sunrays killed it ? It seems weird cause plankton can be refrigerated thus it can whistand temperature changes. What should I consider for next cultures ?
Can I still use the dead culture as a pod food ? Plankton may be dead, but it's still a source of Carbon.

Thanks in advance.

 

[Pistondog]

Maybe it ran out of f2?
What salinity did yiu start with

 

[Joseph_Joe]

Maybe it ran out of f2?
What salinity did yiu start with

I started with 1.020 SG to anticipate water evaporation.
I used the recommended F2 dose. Should I boost it more ?
The thing is that it decayed in a day. It was extremely dark yesterday. If culture was starving, I think that I should have seen it gradually go lighter. But I am not sure, just a simple opinion.

 

[Pistondog]

choices
1. Harvest earlier
2. Reduce light intensity, put a piece of copy paper around phyto jar.
3. Add more f2
I hypothesize you ran out of f2 due to sunlight. Most/some use leds.

 

[Joseph_Joe]

choices
1. Harvest earlier
2. Reduce light intensity, put a piece of copy paper around phyto jar.
3. Add more f2
I hypothesize you ran out of f2 due to sunlight. Most/some use leds.

But then why do harvested cultures doesn't crash down once in the fridge and stay green for like weeks ? Technically without any sun rays and with tiny remaining F2 once in the fridge, all factors are good for a crash. But it won't happen.

 

[Pistondog]

I dont know.

 

[Imrahilwjz]

I think the cultures don't crash in the fridge because they are essentially dormant and using very little energy. They will crash if left indefinitely.

 

[BigAl07]

But then why do harvested cultures doesn't crash down once in the fridge and stay green for like weeks ? Technically without any sun rays and with tiny remaining F2 once in the fridge, all factors are good for a crash. But it won't happen.

As noted by @Imrahilwjz above, the cold in the fridge slows their processes down so much they can live much longer with minimal food/light. They won't live indefinitely in that "suspended state" but they can live a good while.