phytoplankton culture help

[Jakegr]

Originally Posted by donkey77

is it going to be ok if i have it in my fish room or does it need complete darkness, cause my sump light is on 18hrs a day

To maximize growth rate, light the phytoplankton 24/7. It does not need a period with the lights off. The phytoplankton gets its "dark" time as the cell circulates in and out of the inner parts of the culture. I'm not sure what species you have, but typically 100 umol (PAR) is a conservative light intensity for microalgae.

Also, this website details the F/2 medium and gives some information about general algae culture.

https://ncma.bigelow.org/node/79

F/2 can be purchased in bulk from aquatic ecosystems. The 1 gallon jugs of part A/B would last most hobbyists a very long time. To make it easy measuring-wise, you can make pre-mixed "stock-solutions" and keep them in your fridge. This would allow you to add (for example) 1 mL of stock solution per L of culture to achieve the appropriate concentration.

http://www.aquaticeco.com/subcategor...F-2-Algae-Feed

[donkey77]

so i have to keep my f2 in the fridge , and why does everybody say 16hrs light and 8 h darkness iam confuzed

[Myka]

Originally Posted by donkey77

why does everybody say 16hrs light and 8 h darkness iam confuzed

I always get best results 16 hours on, 8 hours off.

[donkey77]

myka do you keep yours in the fridge too

[Myka]

Originally Posted by donkey77

myka do you keep yours in the fridge too

The f/2? Yes. I haven't had any luck with f/2 though, I think I got a bad batch. I've been using Miracle Grow and Kent Essential Elements, but I worry that f/2 might make the phyto more nutritious, so I'm going to order new f/2 and try it...eventually.

I don't put any phyto in the fridge.

[Jakegr]

Originally Posted by Myka

I always get best results 16 hours on, 8 hours off.

You are likely using too intense of light then. From a physiological standpoint there is no reason to give microalgae 8 hours of darkness. The dark reactions occur on the order of milliseconds and the light reactions occur pretty much instantaneously. The cells get their "dark" period on the inside of the reactor, when they are not illuminated. If you give the algae 8 hours of darkness, they are likely switching to respiration, which will lower growth rates. Try reducing light intensity to 30 umol on a 24/7 schedule, and then slowly ramping up the light intensity over time.

[mameroo2000]

As a plant to grow properly you need to provided the right habitat, which depends of the species they need usually a light intensity of 2500-5000 lux (250-500 footcandles) Conversion of foot candles to lux or lumens is: one ft. c = 10.8 lumens or lux, for nannochloropsis oculta (the mos common phyto to culture) you need 2,500-8,000 lux...You would get that intensity in a led warm white light on a 16 hours on that will allow the micro algae to breething co2 and you need 8 hours in full darkness for breething oxygene...like this system you will have a balance with your PH level inside the reactor chamber. Light shading by algae cells would become limiting as density increase, at high densities incoming light is shade from all but the cells currently at the outer surface of the reactor, that is mean is time to harvest the culture.

[Jakegr]

Originally Posted by mameroo2000

As a plant to grow properly you need to provided the right habitat, which depends of the species they need usually a light intensity of 2500-5000 lux (250-500 footcandles) Conversion of foot candles to lux or lumens is: one ft. c = 10.8 lumens or lux, for nannochloropsis oculta (the mos common phyto to culture) you need 2,500-8,000 lux...You would get that intensity in a led warm white light on a 16 hours on that will allow the micro algae to breething co2 and you need 8 hours in full darkness for breething oxygene...like this system you will have a balance with your PH level inside the reactor chamber. Light shading by algae cells would become limiting as density increase, at high densities incoming light is shade from all but the cells currently at the outer surface of the reactor, that is mean is time to harvest the culture.

Microalgae do not require a prolonged period of darkness to "breath oxygen". Microalgae require ATP to fix CO2. They produce ATP only when illuminated, and therefore will not fix CO2 in darkness. As soon as CO2 fixation ceases, growth will also cease. I'm not saying you can't grow microalgae if you give them a dark period, I'm saying growth is maximized if they are illuminated 24/7.

Here are a few references that explain the reasoning, which is firmly based on the well established physiology of plant cells and photosynthesis.

"..long dark periods (i.e., of the order of magnitude of several hours) generally result in biomass loss, as well as decline in growth rates, because microalgae switch to respiration processes; several authors have indeed suggested that a suitable dark period should be of the order of miliseconds (Kommareddy and Anderson 2004)—which would be more appropriately seen as an intermittent cycle"

From - Carvalho et al. 2011. Light requirements in microalgae photobioreactors: an overview of biophotonic aspects. Applied Microbiology and Biotechnology, 89, 1275 - 1288.

"This internal shading (clearly visible in that light does not pass through the culture’s optical path, being essentially fully absorbed in the outer surfaces), results in cells receiving light intermit- tently, a phenomenon augmented by the fact that light energy attenuates exponentially in passing through the culture column. The higher the cell density, the shorter the depth light penetrates into the culture. Two light zones are thereby established in the culture: the outer illuminated volume, in which light is sufficient to support photosynthesis (i.e. the photic zone); and the dark volume, in which net photosynthetic productivity cannot take place, since light intensity is below the compensation point (Fig. 8.1). The higher the population density (and the longer the optical path), the more complex it becomes to address the basic requirements for efficient utilization of strong light, i.e. an even distribution of the available light to all cells in the culture, at an optimal dose per cell (to be elucidated somewhat later).

Clearly then, when mutual shading prevails, cells are not exposed to continuous illumination but rather to cycles of light and darkness (L–D cycle), which may take scores of milliseconds to a few seconds to complete, depending on the optical path and the extent of turbulence in the culture. The endless combinations of light intermittency expressed in L–D cycles to which the individual cells are exposed at a given instant, relate to two basic para- meters: first, the ratio between the light and the dark period in the cycle and second, the frequency of the cycle. As shall be elucidated, the higher the frequency of the L–D cycle, the more efficient strong light may be used for photosynthesis."

From Richmond (2005) - page 127/128. "Handbook of Microalgae Culture".

[MitchM]

Jakegr,
Thanks for posting references.
It's helpful to see that.

[Myka]

Originally Posted by Jakegr

You are likely using too intense of light then. From a physiological standpoint there is no reason to give microalgae 8 hours of darkness.

My method works very well for me. I use less electricity and get the same results as 24 hour lighting. Phyto doesn't need a dark period, but it also doesn't need 24 hour lighting. Thanks for the advice though.