Quick and dirty Nannochloropsis culture

nately

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I bought a 500mL Nannochloropsis culture from eBay and thought I'd see if I could keep it alive with a few things I had lying about the house. I couldn't easily get my hands on specific algae culture media, and I wasn't too keen on maintaining a perfectly sterile culture environment, so I wanted to see if the quick and dirty approach works. 3 months later it's turned out pretty well so far!

I thought I'd share my experience for anyone else interested in a less complex Nannochloropsis culture method. I wouldn't recommend this method if you're culturing at scale, or if you're concerned about putting extra nitrate or phosphate (or whatever else might be in the fertiliser) into your tank.

The key points are:
- I used standard plant fertiliser
- Tap water with dechlorinator
- No heater; average temperature about 12-15 degrees celsius (something like 54-59 degrees F)
- 12h photoperiod

Equipment I used:
10L tank
Cheap hang on back pump with filter media removed (similar to this)
Cheap freshwater light (something like this)
Timer (I've had a really good experience with the TP-Link Kasa series of smart plugs/powerboards)
Extremely cheap, no-name plant fertiliser
Blue treasure salt (I got 20kg for $50 AUD)
Refractometer
Dechlorinator

Phyto fertiliser.jpg

Off-brand fertiliser

Method:
I cleaned the tank with soap and water, then rinsed with boiling tap water.
I filled the tank with about 9L of tap water, and put in a few drops of dechlorinator
Added the marine salt to get a standard gravity of 1.20 (was about 200g salt to the 9L of water)
Added 100mL of Nannochloropsis culture
Added a pinch (probably 2-3g) of crushed up fertiliser pellets
Installed the HOB pump to get some water movement
Set the light to a 12h photoperiod

Phyto culture tank.jpg

The (ghetto) setup

Harvesting:
I take about 2L per week of the Nannochloropsis culture. This goes in the fridge (and serves as a backup in case the main culture crashes).
After 2 weeks (i.e. 4L harvested), I add 4L of dechlorinated tap water made to standard gravity ~1.15 to replenish this.
With each top-up I add another pinch of fertiliser.

Phyto culture bottle.jpg

The end result

Results:
It took about 4-5 days to notice that the water had become a darker green
After about 3 harvests (i.e. 3 weeks), the green was about the same intensity as the culture from eBay
In my tank:
- I noted an increase in copepods, and especially mysid shrimp (literally thousands of these) in my refugium (dosing ~2L per week into a 200L system)
- Nitrate and phosphate remain 0
- Corals look happy enough, but it might be too early to tell whether they've responded

My main aim was to maintain the culture over time without crashing, rather than keeping production at maximum.
After a water top-up, it seems to reach maximum density after about 2-3 days - and stays that way for the next 11-12 days until the next top-up
It remains to be seen whether the culture can survive at this density during the warmer months (the end of the year in my part of the world), but I suspect it'll be OK.


Mysid shrimp hanging around my return pump. Had a population explosion a few weeks after dosing Nannochloropsis

I know that Nannochloropsis is pretty easy to culture, and is probably not the best phytoplankton strain available for our purposes.
What this demonstrates is that it's really easy!

What do you think? Have I just been lucky so far? Am I risking a disastrous contamination of my culture and tank? Or is this pretty consistent with everyone else's experience?
 
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nately

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One problem that might happen over time:

How do you know that what you have is still Nannochloropsis? And not Synechococcus or something else that could have infected your culture and taken over?

Not that huge of a deal, but something to think about
That's a good point - I won't know unless there's an obvious change in odour or similar.

I'll break out the microscope in the next few days and see what's growing.
 
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nately

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Under the microscope:

Nanno microscope.jpg


With the poor resolving power of my equipment, I could see:
- a single species/morphology in the sample
- green, spherical, non-motile organisms

And that's all I can really say. Looks consistent with Nannochloropsis, but could be anything.

My theory is that with high concentrations of Nannochloropsis that rapidly take up all available nutrients, other primary producers are unable to take hold (despite my lax infection-control practices).

What I can say is that you can grow green-coloured water using plant fertiliser, rather than the expensive algae-specific stuff!

I'll update if anything disastrous happens.
 

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I used to culture Nano but I don't any more: it's not the best of algae - more prone to crushes and less nuticious for various critters/filter feeders in tank. I culture Tetraselmis nowadays with my DIY culturing station..
 
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Unless you have a 20 foot tank - you don't actually need that much algae. It's best to have just-about-right amount,rather than excess of it - phychologically it's difficult to discard excess supply.

I culture 1.5L a week using the below mini-station (35cmx30cmx30cm) - it's enough to dose about 200ml a day for my 4 foot tank.

My rocks are filled with yellow sponges and I have lots of filter feeders everywhere...

20210916_185034.jpg

20210916_185107.jpg
 
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nately

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As for fertiliser - I don't quite understand why try to save a few dollars/pounds on F/2 fertiliser - the bottle I bought 2 years ago is still about half used..
Your setup looks great!

Yes that's true. I just used what I had lying around the house. I'm sure F/2 has everything in the right ratio for algae culture, but I was curious to see whether it's essential to the process (and clearly it's not).

You're right about dosing, too. I figure I'd probably see a culture crash if I diluted the culture any less often than I currently do (40% every 2 weeks). So I put that all into my tank - no idea if that's too much or too little.

The amount I dose produces a little haziness for about an hour, which then gives way to crystal clear water, so I figure I can't be doing too much harm.

How did you arrive at your dosing regimen?
 
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Your setup looks great!

Yes that's true. I just used what I had lying around the house. I'm sure F/2 has everything in the right ratio for algae culture, but I was curious to see whether it's essential to the process (and clearly it's not).

You're right about dosing, too. I figure I'd probably see a culture crash if I diluted the culture any less often than I currently do (40% every 2 weeks). So I put that all into my tank - no idea if that's too much or too little.

The amount I dose produces a little haziness for about an hour, which then gives way to crystal clear water, so I figure I can't be doing too much harm.

How did you arrive at your dosing regimen?
Just by trial-an-error over time understanding of how much is OK for the tank. There isn't a single amount that will tell you how much is "too much", it all depends on tank but I think 200ml a day is generally "about right" as I read it from different threads. Also when dosing phyto -you need to start with very small dose, maybe 20ml/day - and gradually increase it over time (maybe 10ml each week extra). If you don't increase it gradually - you risk creating a phosphates shock - that does not fare well for LPS.
 

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Your setup looks great!

Yes that's true. I just used what I had lying around the house. I'm sure F/2 has everything in the right ratio for algae culture, but I was curious to see whether it's essential to the process (and clearly it's not).

You're right about dosing, too. I figure I'd probably see a culture crash if I diluted the culture any less often than I currently do (40% every 2 weeks). So I put that all into my tank - no idea if that's too much or too little.

The amount I dose produces a little haziness for about an hour, which then gives way to crystal clear water, so I figure I can't be doing too much harm.

How did you arrive at your dosing regimen?
As for dilution - I harvest 75% (anywhere between 7 days and 10 days' period), i.e. dilute the new culture 1 part culture/3 parts new water.
 
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nately

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Many fertilizers contain trace amounts of copper which may be detrimental in the long run. (I'm speaking from online research, not experience)
True, I did worry about this. I'm counting on macroalgae export to manage a multitude of sins (including copper accumulation). It remains to be seen whether this will be sufficient over the long run.
 
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