Precise Phototrophic Cultivation of Algae and Cyanobacteria
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Shipping policy

Shipping Policy

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Return Procedure

Before returning any instrument to PSI:

  • Make sure that the instrument is in fact faulty and has not just been set up improperly.
  • Contact PSI support(at) before sending anything back. You will be given the RMA number, which must be clearly marked on the outside of the shipped container.
  • When sending the faulty device back to PSI, please pack it very carefully. Use a have duty box and lots of wrapping/foaming material.
  • If the returned instrument is damaged during shipment due to insufficient packing, PSI will have to charge the repair (or its part) as a non-warranty one.
  • If you have encountered a program failure, we would need a printed copy of any faults you have seen, including how to reproduce them. Include it into the return package along with your mailing address.
  • Include a copy of the Invoice on which the product was shipped to you.
  • All returns must be shipped prepaid. Unpaid packages will not be accepted.
  • In case of questions contact us by E-mail: support(at) or shipping(at), by phone: +420 511 440 034, +420 511 440 032,+420 511 440 022, +420 388 440 046, or by fax: +420 511 440 901.
  • How to find serial number, firmware number or software version of the Multi-Cultivator?
  • The serial number is marked on the label on the rear side of the Multi-Cultivator (for example: SN-MC-1000-337). Please note, the serial numbers of the Multi-Cultivator and its power supply must fit. The firmware number can be found in the main menu of the control panel that is placed on the front side of the Multi-Cultivator. Go to: Settings >> Device Info >> FW Version (for example: The software version including the active license type is stated in Service Information context menu in the main node of the Control Software Client (for example: License type: ADVANCED; Version: 0.7.14-1524)

  • What is the best position of the aeration glass straw in the test tubes?
  • The best position of the aeration glass straw is on either side of the vessel (because the OD sensor is aligned with the center of each cultivation tube). Please, check that all cultivation vessels, silicone plugs and aeration glass tubing are at the same position. All aeration glass tubing should be in the same distance from the bottom of the cultivation vessel because the position of the aeration tubing end affects the size of the bubbles. Optimal position of the end is about 0.5 mm from the bottom of the vessel. Ensure the end of the glass straw is sufficiently away from the bottom of the vessel not to hinder the bubbles coming out of the straw. Ensure that there are no kinks in the silicon tubing that may impede the flow of gas.

  • Is it possible to replace the fragile glass aeration straws?
  • Yes, the fragile glass aeration straws can be replaced by stainless steel aeration tubes that are easier and safer in manipulation. Based on our testing, the algae growth dynamics, growth rates and final optical density are comparable regardless if glass or stainless steel aeration straws are used. Also the CO2 saturation time was similar irrespective of glass or stainless steel straws use. The test were performed under standard cultivation conditions.

  • How to adjust exactly same air flow rate into each testing tube?
  • Moreover, a set of mini flowmeters installed on the tubing between the manual taps and aeration glass straws could help to improve the control of the flow rates a little bit. Please remember, the aeration system of the individual testing vessels is interconnected. That’s why the conditions that influence a pressure and flow rate into one testing vessel will simultaneously influence also other testing vessels. In general, the Multi-Cultivator is a low-cost device and therefore it doesn't include precise control of the gas flow rate into each tube.

  • Is the main aeration dispenser tube (black tube with 8 small valves) autoclavable?
  • The humidifier (1L glass bottle with cap) and silicone tubes can be autoclaved at 121°C. The aeration tube with valves can be autoclaved at 75 C only. The aeration dispenser can also be sterilized with 70% ethanol. Please, note that the backpressure valve (Teflon runner) is neither autoclavable nor sterilizeable by ethanol.

  • How are performed the optical density measurements?
  • The method is based on light absorption / scattering of certain wavelengths (680 and 720 nm) by chlorophyll and cells. In general, the OD 680 is linked to the chlorophyll absorption and can be used for an estimation of chlorophyll concentration whereas OD 720 determines light scattering on particles and can serve as a proxy for biomass growth. The OD is defined as -Log(I/Io) where Io is the irradiance that is transmitted through the cuvette filled with medium without algae or other organisms. This quantity must be measured as the reference. I is the irradiance transmitted through the cuvette with algal or cyanobacterial suspension in which OD is measured. Log is the decadic logarithm of the I/Io ratio. Thus, optical density OD = 1 means that light at the respective wavelength is attenuated by algae or cyanos 10 times relative to the reference. With OD = 2, the attenuation relative to the reference is 100 times. Please note, that the optical path of the test tubes is ca. 27 mm. The whole process of OD measurement is automated in the Multi-Cultivator. The OD can be measured manually one time through the front control panel, or a protocol can be set where the OD measurements are performed in periodic intervals. Measured data can be later downloaded to a computer via the OD Viewer or displayed in graph in real time via the Photobioreactor Control Software (optional).

  • What is the maximum optical density that can be measured? Is the OD measurement linear?
  • Based on our testing, the OD 680 was usually found to be linear in the range 0.1 – 0.9 (up to 1.0). The OD 720 was usually linear in the range 0.05 – 0.4 (up to 0.5). The linearity of individual devices may differ slightly. Non-linear measurements can go up to about 2.5 and 1 for OD 680 and 720, respectively. However the data distortion is considerable at this level. The optical path of the OD measurement is ca. 27 mm.

  • Why the identical algal biomass concentration shows slightly different OD in various cultivation slots?
  • The variability of the OD reading in different cultivation slots is given especially by an improper or insufficient mixing before the distribution of the algal inoculum into individual cultivation vessels. A part of the variability is given also by an alignment of the OD measurement system in the individual slots (i.e. alignment of the measuring LED and detector) and by a tubular and no exactly identical shape of the experimental vessels. Also the biomass concentration influences the OD reading variability probably due to the scattered light absorption (the lower biomass concentration the higher relative OD reading variability). The biomass OD reading variability was determined as the relative standard deviation of the OD 680 measurement. The relative standard deviation doesn’t exceed 10% and 5% for OD 680 readings around 0.1 and 1, respectively.

  • What are the detection and quantification limits of the OD measurements?
  • The detection and quantification limits were estimated from the mean of the blank and related standard deviation of the measurement. The detection limit was determined as triple of the standard deviation; the quantification limit as tenfold of the standard deviation. The OD detection and quantification limit for Multi-Cultivator is 0.01 and 0.04, respectively.

  • Is there any increased evaporation from the test tubes during the experiment? Is the water level in the test tubes topped up automatically, allowing minimal user supervision?
  • The humidified sparging air along with the condensation system grant minimal medium evaporation. That’s why there is no any automatic water level detection in the test tubes and no medium is added during a batch-designed experiment automatically. Based on our testing, there was no significant evaporation under temperature of 27°C after one week of cultivation (ambient temperature around 22°C). During a high-temperature cultivation at 60°C, the evaporation from the test tubes was on average 5 mL (6.4%) after one week. The evaporation usually fluctuated between 1 – 10 mL (2 – 11%) in the individual test tubes. To avoid undesirable evaporation, it is crucial to seal up the vessels (stoppers, tubing and connections) properly. Please remember, that the evaporation is highly dependent on the cultivation and ambient temperature. Also other conditions as for example: air sparging intensity (lower intensity = significantly lower evaporation), draught from the air-conditioner, tubing material, etc. may influence the result significantly.

  • Is there any temperature gradient among the testing tubes?
  • The testing tubes are immersed in a thermostatic water bath in order to control and keep the required cultivation temperature. The temperature homogeneity of the water bath and thus also of the testing tubes is ensured by proper water mixing with the water pump.

  • Is it possible to keep the cultivation temperature below the 15°C?
  • Yes, this may possible under special circumstances. With a specific firmware modification the cultivation temperature can be set down to 5oC. However, the device itself is not designed (insulated) for such a type of cultivation and also the cooling system doesn’t provide sufficient cooling capacity. Therefore it is necessary to keep also the ambient temperature at low level to ensure a low-tempered cultivation.

  • Is there any significant difference between algal growth dynamics under cool white and warm white LED lights?
  • We didn’t identify any really significant difference in growth dynamics of Chlorella vulgaris and Cyanothece sp. between cultivation under cool white and warm white LED illumination during the linear growth phase. Also vital absorbance spectra of biomass were qualitatively comparable. A common cultivation conditions without any particular stress were used during the test.

  • Is there any light interference among the individual cultivation slots?
  • The illumination of the adjacent slots interferes a little bit. Approximately 2% of the illumination may penetrate into the adjacent slot.
  • How to find serial number, firmware number or software version of the Photobioreactor?
  • The serial number is marked on the label on the rear side of the Photobioreactor (for example: SN-FMT-WR-337). Please note, the serial numbers of the Photobioreactor and its power supply must fit. The firmware number can be found in the main menu of the control panel that is placed on the front side of the Multi-Cultivator. Go to: Settings >> Device Info >> BR FW Version (for example: and Settings >> Device Info >> TR FW Version (for example: The software version including the active license type is stated in the Service Information in the main node of the Control Software Client (for example: License type: ADVANCED; Version: 0.7.14-1524).

  • Which Photobioreactor panel (blue/red or white/red) works better for cyanobacteria growth?
  • Cyanobacteria use phycobilins as additional photosynthetic pigments with absorption maximum in red region, therefore cyanobacteria are more sensitive to the red light and usually a combination of white/red light panel is recommended for cyanobacterial cultivation.

  • Is it possible to measure pH, dO2 and dCO2 simultaneously?
  • Yes, this is possible. There are three ports in the lid that are intended for pH/temp, dO2 and dCO2 sensors. It is necessary to purchase each sensor module separately. The sensors values are recorded automatically by the Photobioreactor Control Software.

  • Is it possible to calibrate pH, O2 and CO2 sensors by the help of the Photobioreactor Control Software?
  • Yes, this is possible through a context menu of each sensor. Simple pH, dO2 and dCO2 calibrations and also temperature dependent dO2 calibration are available.

  • What is the recommended flow rate of the aeration?
  • The aeration flow rate depends on the size of the cultivation vessel and also on the experimental and cultivation organisms’ demands. Usually, we use aeration flow rates around 1 L/min for Multi-Cultivator, 1.3 L/min for Multi-Cultivator coupled with the Turbidostat, 250 mL/min for 400 mL PBR, around 500 mL for 1000 mL PBR. The mentioned levels are only illustrated and may differ significantly based on the different experimental requirements.

  • Is it possible to connect more Photobioreactors to one Gas Mixing System?
  • In general, this is possible. However, this configuration is not that accurate as the connection of one PBR with one GMS 150 unit which is highly recommended. The connection can be arranged through a simple branching of the output GMS tubing. We recommend to purchase additional air PWM pumps (optional) and valves with mini flow-meters (not in our offer) to adjust the gas flow rates into the individual PBR.

  • Is there any excessive evaporation from the Photobioreactor during the cultivation? Have you addressed this issue somehow?
  • We are routinely using the gas humidifier (bottle with distilled H2O) on tubing line before each Photobioreactor. Therefore we don’t experience any considerable evaporation under common cultivation conditions in the air conditioned laboratory.

  • What is the pressure rating of the Photobioreactor vessel?
  • Maximum inner pressure inside the 400 mL and 1 L vessels should be always below 2 bars (alternatively below 1.5 bar for 3 L vessel) during the cultivation. All cultivation cuvettes are autoclavable under 121°C at 101 kPa above the atmospheric pressure unless at least one sensor port is open (covered with the aluminum foil).
  • Is there a chance to see how the Photobioreactor Control Software works?
  • Yes, there are video tutorials in the product Gallery on the PSI web site.

Large-Scale PBRs

  • Is there a chance to see how new Photobioreactor Software works?
  • Yes, there are video tutorials in the Video Gallery on the PSI web site.