nanno growing brown algae/diatoms

[grahf11]

hi guys! im culturing nannochloropsis using 2 liter bottles and a few more sizes. I clean the bottle with bleach then microwave them for 15 seconds. i clean them every after 7 days before innoculation. if the bottle is very dirty, i change it. after a few tries like 3-4x, my culture grow brown algae. then eventually crash. what seems to be the problem? where are those diatoms coming from? i use 2x 40w flourescent bulbs 16 on 8 off using BOILED natural sea water. another problem is, after a few tries, my nanno wont turn as green as before. they start turning yellowish green then eventually crash too. is it because im using NSW? i boil all so all organisms die. is it better to use rock salt + RO water rather than NSW? i use coffee filters to remove the solid particles before innoculating the nanno to a new container.

[Kmiec123]

I would use Bleach to sterilize my water, then Sodium Thiosulfate to de-chlorinate the water....much easier than dealing with boiling or microwaves. If memory serves me, I believe i was able to filter the nanno and start it back up....may have used coffee filters of a 10 micro...don't remember.
6g Sodium Thiosulfate per 100ml of RO will give you a one-one ratio...meaning if you add 4ml Clorox you will need to add 4ml of the solution to remove that amount of bleach.
Hope this works for you.
Carl

[grahf11]

ok will try to see where i can get the sodium thiosulfate here. do you know where and why im getting diatoms on my nanno culture?

[Kmiec123]

Bad culture or airborne likely...do yoy have a airfilter on your air pump?

[Kmiec123]

...

[grahf11]

no i dont have. yeah probably that. im not sure if i can buy airfilter for my airpump here. ill try to get some. my culture when it arrived here before were very very green. so it shouldnt be a bad culture at start. probably the dirty air inside and or the boiled seawater.

[Kmiec123]

Make your own filter on the intake with cotton and charcoal.

[onsan]

medical or food grade hydrogen peroxide is ideal to use for chlorine neutralisation, reaction is H2O2 + NaOCl -> H2O + NaCl +O2, aka oxygenated NSW. Or just leave it in the sun for a day or two.
if you're sure its diatoms you could use some Aluminium Oxide in your NSW treatment method, it will soak up the Silica ( as well as Phosphate) which a lack of will become a limiting nutrient for diatoms (req for shell construction).
Maybe combine with the filter method with short incubation cycles and small inoculations and over a period of time you should be able to eliminate diatoms from your culture.

[grahf11]

ok will try to get aluminum oxide. i wonder where can i get them?

i will also try a cheap saltmix instead of using NSW and it might help a little too.