AK Culturi-M Pro
Set up your Culturi-M Pro
Four steps to get the reactor ready, then pick your culture. Phytoplankton runs in batches, copepods build over weeks, and you only see the steps for the one you are running.
- 26 steps
- 40 min hands on
- 5 to 7 days per batch
- 2 L working volume volume
0 of 26 done
What are you culturing?
Which sounds like you?
Everyone starts here
Set up once
Four steps, done once when the unit arrives, whichever culture you are running. The only part that needs real care is the glass.
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Get the unit out of the box and the lid off the vessel without stressing the glass.
The vessel is only held by friction
The glass vessel is not fixed to the base unit. It sits in place by friction alone, so treat it exactly as you would any other loose piece of glassware.
- Open the box from the top.
- Remove the protective packaging from inside the box.
- Grasp the top of the unit and lift it out.
- Unwrap it carefully. The glass vessel can detach from the light base as the wrapping comes off.
- Separate the vessel from the base. Hold it with both hands, thumbs together under the lid and index fingers on the back of the lid, then pull back with your fingers while pushing up with your thumbs. The lid will release.
- Take the contents out of the vessel.
- Plug the light unit into a power socket, but leave it switched off.
Newer units: snip the pump's zip tie
Some newer units ship with a zip tie holding the air pump in place, so it is not thrown around on its stabilisers in transit. Snip the tie and pull it out before you run the pump.
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Slide the glass tube through the seal slowly, and stop a finger's width off the bottom.
You need
Microfibre cloth, food-safe lubricant if needed
- Push the tubing through the seal slowly, with about the weight of one or two fingers behind it. Lubricant is usually not needed.
- Stop when the end of the tube sits roughly one finger width above the bottom of the vessel.
- If it needs more slip, use a food-safe lubricant: USP or food-grade glycerin, or a little sterile water-based lubricant. Cooking oil is a last resort.
- Wipe the tubing clean inside and out to remove any lubricant residue before use.
Forcing the tube in too fast or too deep can fracture the base of the vessel, and once the vessel is full of water a fracture there can take the light unit and your bench with it.
Every glass part on this unit deserves the same care: the vessel, the lid and the rigid tubing are all breakable, and breakage after delivery is not covered by the warranty.
Tubing out before the lid comes off
Always remove the rigid tubing before you take the lid off the vessel. This matters most with the Pod Core fitted: levering the lid with the tubing still in place risks breaking the tube or the vessel, and cutting yourself on the way.
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Pair the light with Smart Life over 2.4GHz Wi-Fi.
You need
Smart Life app, 2.4GHz Wi-Fi
2.4GHz only
The light will not join a 5GHz network. If your router broadcasts one name for both bands, split them or switch to 2.4GHz long enough to finish pairing.
- Install Smart Life - Smart Living from the App Store or Google Play, then create an account and log in.
- Switch the light on, then flick it on and off seven times: on, off, on, off, on, off, on. It flashes when it is ready to pair.
- Open Smart Life and tap Add Device. It should find the light on its own, so tap Add when it appears.
- Choose your 2.4GHz network, enter the Wi-Fi password, and tap Next.
- Rename the device to something you will recognize.
If the light does not appear by itself, add it by hand: Add Device, then Lighting, then Light Source (Wi-Fi).
The name you set at the end is the one the app and any voice assistant will use, so keep it short and easy to say.
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Vinegar or diluted isopropyl. This is the step that decides whether the culture lives.
You need
White vinegar or 70% isopropyl, microfibre cloth
Do not skip this step
Clean cultures are not possible without clean sterilization. Sterilize at every opportunity and you remove most of the reasons cultures crash.
White vinegar
- Mix 1:1 white vinegar and water in the 2 L vessel, for example 1 L of each.
- Attach the lid.
- Swirl vigorously every few minutes, reversing direction as you go, so every surface is covered including the inside of the lid and the rigid tubing.
- After 15 minutes, rinse with clean water until you can no longer smell vinegar, then dry everything with the microfibre cloth provided.
Diluted isopropyl alcohol
- If you have 100% isopropyl, dilute it to 70% with water so it does not evaporate before it works.
- Spray the vessel and the inside of the lid thoroughly, soaking every surface including the rigid tubing and seals.
- Attach the lid and wait 3 to 5 minutes.
- Remove the lid using the two-thumb release from step 1.
- Dry everything with the microfibre cloth. Once you can no longer smell alcohol, it is ready.
There are tougher methods than these two, ranging up to chemicals that are genuinely dangerous to skin and eyes. We have stuck to the simple and safe options here. If you are confident, they are worth researching.
Whatever you use, avoid:
- chemical contact with the rubber seals
- anything that leaves a smell, slickness, film or residue behind
- scented products of any kind, including items washed with laundry detergent, stain remover or soap
No boiling water
Do not add boiling water to the vessel or change its temperature quickly. Thermal shock fractures glass.
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Synthetic salt at 1.024 to 1.026 sg. Natural seawater has to be sterilized first.
You need
Synthetic salt mix, fresh water, refractometer
- Mix synthetic salt with fresh water. Synthetic is what we recommend, because you do not have to sterilize it.
- Match the salinity of the starter culture you have. Ask your supplier for the exact specific gravity, or use 1.024 to 1.026 sg (34 to 35 ppt), which is perfectly safe.
- If natural seawater is your only option, neutralize the life in it with chlorine first, then neutralize the chlorine with thiosulphate.
You have dechlorinated correctly if you can smell chlorine before adding thiosulphate and not after.
Sterilising natural seawater matters because whatever is living in it will happily eat what you are trying to grow.
Phytoplankton
The phytoplankton cycle
Seven steps you repeat for each batch. Roughly ten minutes of work, then five to seven days of growing.
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1.8 L of prepared saltwater, leaving room for the starter culture.
- Fill the glass vessel with 1.8 L of clean, prepared saltwater.
- Leave the remaining volume for your starter culture.
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Guillard's F/2 for most strains, then mix it through before anything else goes in.
You need
Guillard's F/2
- Use Guillard's F/2 for most strains, including nannochloropsis and tetraselmis. Follow its own dosing instructions for the volume in the vessel.
- Stir or swirl gently so the fertilizer is evenly distributed. Do not stir with anything that has not been sterilized.
Distributing the fertilizer is not strictly essential, but we recommend it. A concentrated pocket of fertilizer sitting against sensitive cell walls can do damage that an evenly mixed vessel never will.
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200 mL of starter into the 1.8 L of water, then switch the light on.
- Turn on the integrated light if it is not already on.
- Add 200 mL of starter culture to the 1.8 L of saltwater, a 9:1 ratio.
The honest minimum is one cell. That really is all it takes.
We recommend far more because a 9:1 water to starter ratio is the safe margin. For the Culturi-M Pro that is 1.8 L of saltwater to 200 mL of starter, which is a generous start. You would very likely still succeed with 50 mL.
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Air pump on, gate valve wide open. Phytoplankton likes it vigorous.
- Turn on the air pump.
- Open the gate valve on the rigid tubing fully, or as far as it will go.
Strong aeration keeps the culture mixed, improves gas exchange and stops cells settling on the bottom. For the common phytoplankton strains this level of airflow is what supports consistent growth.
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Slow for a day or two, then obvious. Keep it between 68 and 78 F.
- Expect slow darkening for the first day or two, then a noticeable change day after day.
- Hold the water between 68 and 78 F (20 to 26 C).
- If the temperature is getting too high, lower the light brightness to cut the heat it puts into the water.
Growing too fast? Shorten the time it spends under light. Too slow? Lengthen it.
You can also experiment with more fertilizer to reach a higher density.
Depending on your light schedule and brightness you may hit harvest point earlier than the timeline suggests. If you do, harvest as soon as you can.
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Day five to seven, into a clean 2 L bottle and straight into the fridge.
You need
Clean 2 L bottle
- Harvest around day 5 to 7, when density and health peak.
- Pour the contents of the vessel into a clean 2 L bottle.
- Refrigerate it unless you are using it immediately.
Refrigeration prolongs life significantly, and keeping air exposure to a minimum helps too.
Avoid collecting the dead and dying cells that settle at the bottom. The healthy phytoplankton is in the water column.
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Sterilize everything again before you refill. Skipping this is how cultures die.
- After every harvest, sterilize everything again exactly as you did in the setup phase.
- Once it is clean and dry, start again from filling the vessel.
The point of the reset is to clear out airborne bacteria that found their way in during the last cycle, before they get a chance to establish themselves on the next one.
This is the step people skip
It seems unnecessary, and it is the single most reliable way to ruin the batches that follow. In our experience, neglecting the reset starts the clock on a culture's downfall.
After your first harvest
Easy mode: stretch it to a month
Run the cycle above once, properly, and harvest it. From that first clean harvest you bank a backup, and from there you can stretch the next few weeks without sterilizing between every batch. We would rather you did. This is the version for people whose week does not allow it.
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Set aside about 100 mL from the very first harvest off a clean vessel. That is the cleanest culture you will have all month, and it is what you restart from at the end.
You need
A small sterile bottle or jar with a lid
This step is the whole plan
Skip it and easy mode has no exit. When the vessel finally turns, and it will, you would be starting again from a bottle you have to buy.
- Take the backup from your first harvest, straight off a freshly sterilized vessel. Not the second, not the third.
- Fill a small sterile container, leaving a little air at the top.
- Seal it, label it with the date, and keep it in the fridge, out of the light.
- Leave it alone. This is not for dosing. It is the culture you restart from.
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Instead of emptying and sterilizing, you leave enough behind to seed the next batch.
- Harvest when the culture is dark and dense, the same as you normally would.
- Take most of the vessel, but leave roughly a fifth behind as the starter for the next run.
- Use what you harvested within a few days, or refrigerate it.
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The minimum you should do between harvests in easy mode. It will not sterilize anything, but it clears the film and the salt creep that bacteria live on.
You need
Fresh RO water
- Pour the RO down the inside wall of the vessel and swirl it around the waterline, where the residue collects.
- Rinse the rigid tubing through as well.
- Tip it out. Do not dry it with anything that has been sitting around.
A rinse is not a clean
This buys you time, it does not reset the vessel. The bacteria load still climbs with every cycle, which is why easy mode has a hard stop.
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Fresh saltwater onto the starter you left behind, then feed it.
You need
Prepared saltwater, F/2 fertilizer
- Top the vessel back up to the 2 L mark with fresh prepared saltwater.
- Add the same dose of F/2 you would use for a full batch.
- Put the lid back on, open the airflow, and carry on as normal.
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Each cycle carries more bacteria than the last. Two or three top-ups is about as far as this goes before the culture is no longer really yours.
- Repeat harvest, rinse, top up and feed for two or three more cycles.
- Watch it. Cloudiness that is not green, a smell, or a culture that stops darkening means stop now rather than at the end of the month.
Do not keep pushing it
Past three or four cycles you are culturing bacteria with some phytoplankton in it. It will crash, and it will take the vessel and your week with it.
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Once a month, do the proper job: full clean, full sterilize, and start again from the 100 mL you banked on day one.
You need
White vinegar or 70% isopropyl, microfiber cloth, your banked backup
- Empty the vessel completely and strip the lid down.
- Run the full sterilize step from the setup phase, including the rigid tubing and seals.
- Fill with fresh prepared saltwater and fertilize as normal.
- Pitch your banked backup as the starter, not the tired culture you just poured out.
- Take a fresh backup from this batch's first harvest, and you are set for another month.
Back where you started, on purpose
The month resets cleanly because the culture you pitch has not been through any of it. That is the whole trick.
Copepods
The copepod culture
A copepod culture is a slow build, not a batch. Expect two to three weeks of very little before the population takes off around week four.
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Copepods eat phytoplankton daily. Sort that out before the pods arrive.
- Plan for 10 to 50 mL of phytoplankton per day, depending on culture density. More if rotifers are present, which is common and perfectly fine.
- Many growers run a second Culturi-M Pro or a Culturi-S Pro purely for phytoplankton so they can keep up.
- Source copepods from a reputable vendor, and start the culture with the water they arrive in where you can. It reduces the environmental change.
- If you bought the Pod Core, gently place it into the glass vessel before the next step.
Copepod cultures go through a settling-in period as they adjust to their new environment. It is essentially environmental shock and can take 2 to 3 weeks before the culture establishes. Do not be discouraged by small numbers early on; meaningful growth often is not visible until around week 4.
What you are looking for in that period is ongoing life. As long as you can spot the occasional copepod moving through the culture, it is still active. A female carrying eggs in her brood sack is an especially good sign.
Avoid bottles containing detritus worms, flatworms, hydroids or anything else clearly not a copepod. Some visible detritus is normal and is often clumped phytoplankton cells. If you are unsure what you are looking at, send it through to us and we will help identify it.
Copepods are hardy and tolerate a fairly wide range of temperatures and salinities. In most cases acclimation is not necessary.
Pod Core owners, read this
With the Pod Core fitted, fully retract or remove the rigid tubing before removing the lid. The risk of snapping the tubing is much greater with the attachment inserted.
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Start at 100 mL, add the pods, then build the volume by 100 mL a day.
- Add 100 mL of freshly prepared saltwater to the vessel.
- If the bottle came from a vendor you trust and looks free of unrecognized organisms, pour the whole thing in.
- If you would rather be cautious, use a pipette to move across as many copepods as you can while carrying over as little of the original water as possible.
- From here, add 100 mL of fresh saltwater per day until the culture reaches the max fill line.
The exact amount of water introduced at seeding is not especially important. Building the volume gradually expands the culture and its available surface area while keeping environmental stress low.
Remember that every feed adds water too. If the vessel hits the max fill line before the culture is strongly established, remove some water so you can keep feeding.
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Enough to leave the water lightly tinted green. Not dark, not saturated.
You need
Live phytoplankton, nannochloropsis is ideal
- Feed live phytoplankton. Nannochloropsis on its own is more than enough for strong performance and good harvests.
- Judge the amount by color: the water should hold a light green tint, roughly one drop of green food coloring in 2 L of water.
- Adjust with density and water volume rather than following a fixed dose.
There can be value in feeding a blend of strains, but take care. Some have a shorter lifespan than nannochloropsis and will foul the water if they are not eaten in time.
The goal is to keep food available without overloading the vessel or letting excess algae accumulate and degrade water quality.
Pro tip: concentrate the feed
Let phytoplankton settle in a bottle until the cells separate from the water, pour off the clearer water from the top, then swirl what is left to resuspend a dense feed. It lets you add far more nutrition without adding much water, which matters a lot in a copepod culture.
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Two to three bubbles a second. Gentle, not turbulent.
- Turn on the air pump.
- Immediately reduce the airflow at the gate valve until the culture is receiving no more than 2 to 3 bubbles per second.
The goal is gentle aeration without unnecessary turbulence in the vessel. This is the opposite of what phytoplankton wants, so if you run both cultures, do not copy the setting across.
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No harvesting for the first two to three weeks, and do not clean out the detritus.
- Do not harvest until the population has clearly begun to expand.
- Leave the detritus that builds up in the vessel undisturbed.
Detritus building up is completely normal. Attempts to remove it have consistently disrupted the balance of the culture in our experience, and can lead to collapse.
That changes once the culture is established. From then on the detritus is where most of your copepods are living, which is exactly what makes it the easiest thing to harvest.
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6am to 5pm at 5% brightness. Copepods want dim, not dark.
- Run the light from 6:00am to 5:00pm at 5% brightness.
- Raise it to 100% temporarily when you want to inspect density, then put it back.
- With a Pod Core fitted, a slightly higher level can help, but keep the increase modest.
Most copepod species prefer very low light because in the wild light means exposure, and exposure means predators.
White light encourages algae growth and algae can feed copepods, so some light is useful. Too much stresses the culture and works against the conditions they prefer.
A little more light with the Pod Core encourages copepods deeper into the core structure, making better use of the shelter and surface area it provides.
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A benthic culture that is running well usually looks like a ghost town. Stir the detritus before you judge it.
- Turn the light up to 100%.
- Stir the detritus thoroughly so it lifts into the water column.
- Watch everything settle back down, and judge the density from what comes down with it.
- Put the light back to 5% when you are done.
Benthic species live in cover rather than out in open water, so a culture that is doing well normally looks empty. As long as they have been fed, the water is in reasonable shape and the salinity has not crept up, what you are looking at is almost always a culture that is sheltering and breeding down in the detritus and through the Pod Core.
The copepods you can see swimming are a small fraction of what is in there. Judging density off the water column alone will tell you the culture is failing when it is not.
Never call a culture dead on a glance
The culture that looks completely empty is the one people tip out. Stir the detritus up with the light at full and watch it settle first. Growers who were ready to give up routinely find a staggering number of copepods still in there.
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From the end of the settling-in period, take out about a third of the detritus each week and strain it.
You need
100 micron filter, clean container
- Stir the detritus so it lifts, then draw off about a third of it along with the water holding it.
- Pour that through a 100 micron filter. The adults stay on the mesh and the fine detritus goes through.
- Rinse what is on the mesh into the tank, or back into the vessel if you are still building numbers.
- Top the vessel back up with fresh saltwater.
Once the culture is established, the detritus is the best place to harvest from, because that is where the copepods are. Taking out about a third of it each week keeps the vessel from loading up and gives you a harvest at the same time.
Straining is what makes it work. A 100 micron mesh holds the adults back and lets the fine detritus pass through, so you keep the copepods and leave the silt behind.
That third is full of copepods
For a benthic species, a third of the detritus can easily hold thousands of adults. Tip it down the sink unstrained and that is what goes with it.
That is the whole cycle.
Reset your progress whenever you start a fresh batch, or switch paths above to run the other culture.
Reference
Here when you need it
None of this is required reading to get a culture going. It is here for the day something looks wrong, or the day you need the warranty.
Troubleshooting It is not growing, or it crashed
If you are having trouble getting a stable batch going, it helps to step back and remember that phytoplankton is a very simple organism with very simple requirements. Before looking for complicated explanations, start with the fundamentals. These are the most common causes of failure in our own experience.
Contamination
The air around us carries bacteria and other microorganisms, and some of them compete with phytoplankton for the same nutrients. If equipment is not properly sterilized, or the culture sees too much unfiltered air, contamination builds with each harvest until the culture is impure, crashes, or is no longer really a phytoplankton culture at all.
Green cyanobacteria can be mistaken for phytoplankton without a microscope, and excessive cloudiness is often a bacterial bloom rather than density.
Air drying is not recommended. Once equipment is clean, keep it clean and handle it in a way that does not reintroduce contamination.
Unless you are working in an extremely controlled environment, some bacterial presence is inevitable. The goal is not sterility, it is keeping contamination low enough that the phytoplankton keeps outcompeting it. It is also worth keeping a small portion of an earlier, cleaner harvest as a backup in case the main culture starts to decline.
Water source
Anything other than properly prepared synthetic saltwater carries additional risk. Natural seawater and aquarium water introduce bacteria, organics and competing organisms. Do not use them unless they have been chemically sterilized first. There is no practical substitute for that step.
Temperature
Most commonly cultured strains slow down, stress or start to decline once temperatures pass 78 F (26 C), and prolonged exposure at or above that can be lethal. 64 to 77 F (18 to 25 C) is the range for stable growth.
Other possible causes
- incorrect salinity
- poor quality starter culture
- incorrect or degraded fertilizer, or the wrong dosage
About What the Culturi-M Pro is
The AK Culturi-M Pro is the bigger reactor in the Culturi range, running 2 L of phytoplankton, macro-algae or microfauna in a sealed glass vessel with integrated lighting and gate-valve airflow. Built for growers who want steady output without the DIY fuss, whether that is feeding multiple systems or scaling a single culture.
For box contents, specifications and compatible add-ons, including the optional Pod Core for copepod cultures, see the product page.
Safety Working with the glass
This unit contains multiple glass components. Handle all of them with extreme care, including the rigid glass tubing and the vessel itself, to avoid injury or damage.
When inserting the rigid tubing into the seal, lubricant is usually not required. In most cases the tubing slides into place under very light pressure, about the weight of one or two fingers. Insert it slowly and stop when the end sits approximately one finger width above the bottom of the vessel. Forcing it too far or too quickly may fracture the base of the vessel and may also damage the light unit.
If additional slip is needed, use a food-safe lubricant such as USP or food-grade glycerin, or a small amount of sterile water-based lubricant. Cooking oil should only be used as a last resort.
Because the vessel is filled with water in use, any fracture could also result in water damage to the light unit and the surrounding area if proper care is not taken.
After installation, thoroughly wipe the tubing clean on both the inside and outside of the vessel to remove any lubricant residue before use.