Culturing Bryopsis (Part Trois)

I recently had an epiphany about how to grow Bryopsis more efficiently.  In retrospect, it was pretty obvious, and I wonder why it took 2 years to get to this point.

It seemed as though culturing adequate Bryopsis was under control.  However, there’s nothing like 6+ weeks of travel to turn things upside-down.  I had hired a service to come in and keep things going while I was away, but their primary task was to prevent biological meltdown, or worse, a big salty disaster that would have me forever on the naughty list of the facilities people.  I am happy to say, there were no smelly or wet disasters.

Unfortunately, I was not there to give the algae cultures the kind of attention they need, and by the time I was back in the office, the system was overrun with Derbesia, and the slugs had devoured the Bryopsis that I had left for them.  The 20-gallon slug tank and both algae culture tanks were full of felty, green hair algae.  In retrospect, I should have taken photos, but I was more focused on cleaning up the mess and getting ready to teach a summer class.

Over a week or so, I pulled out the algae tanks off the system, cleaned out at least two pounds of green glop, salvaged the remaining Bryopsis, and set the tanks  back up.   Somewhere along the line, I came across a few posts about “algae reactors,”  cylindrical chambers with water flowing through and some sort of light source.  My first thought was “maybe I should buy one of those things.”  Then I remembered that I had two media reactors sitting idly in the basement.  They are clear cylinders, designed to have water flow through them, which is exactly what I wanted.

The amount of Bryopsis remaining was so small that it didn’t seem worthwhile to have two algae tanks.  Instead, I shut down the 10-gallon tank and stuck some of the remaining algae into a reactor. The reactor was hooked up to one of the valves, and connected to the drain, and sat under the grow light where the 10-gallon tank had been.

Two Little Fishies media reactor, with a small wad of Bryopsis held in place by eggcrate. 7/12/17

Within a week or so, it became clear that the experiment was working, so I added the second reactor.  I had enough Bryopsis to harvest some for the slugs, and the culture in the first reactor had seeded a sponge that I could use to start the second reactor.

Second reactor, with a sponge seeded from the Bryopsis in the first. 7/21/17

It was working.  Time to make things a little less clumsy.  I built a rack from 3/4″ PVC, setting the reactors at an angle to optimize the connections to the input valves and drains.

Bryopsis reactors, in their improved configuration. 7/26/17.

Things went so well, I begged a few unused reactors from local aquarists.  This one is from Alan (of unidentified algae fame), and I have one more waiting in the wings.

Three reactors. 8/1/17.

At this point, it was clear that my former method of rearing Bryopsis in aquaria was not very efficient.  Raising Bryopsis in reactors allows me to play with growth parameters, like flow and nutrients, much more easily.  Further, keeping multiple separate cultures will make it much easier to eradicate unwanted algae.  At some point, it should be straightforward to maintain cultures free of unwanted algae and invertebrate pests (I am all for biodiversity, except when it eats slug larvae) by UV sterilizing the water going into the chambers.

As far as I can tell, this was a successful experiment, so I converted the 15 gallon algae tank into the second slug tank, shutting down the 10-gallon slug tank.

When I walked in today, the system had two slug tanks (top and middle left), and one remaining algae tank (top right)

Elysia system before rearrangement. 8/5/17.

Five hours of cleaning and rearranging later, there were two slug tanks and three algae reactors.  In the process, the system now has two fewer circulation pumps and one fewer light fixture.

Current slug system arrangement. Two tanks for slugs and and their food on top, three reactors in the middle, and room to expand. 8/5/17.

In the future, you can expect a few more reactors.  Now it’s time to play with parameters to maximize algae growth.  Maybe we’ll finally see some consistent egg production from the slugs.


  1. Reply
    susanne August 5, 2017

    I like it – though the bryopsis in an algae scrubber (in tank) arrangement is rather nice, too.
    One questions – what’s the back end to the reactors? I mean, these are not circulating minitanks, but have to have a bigger reservoir somewhere, right?
    What GPH rating do you use for the circulation pumps to get enough flow through the reactors to keep the bryopsis happy?

    Very much looking forward to your future bryopsis optimizations as I would love to be able to have multi-generational slug tanks but without the complete mess these trun into over time.

    • Reply
      Dave August 6, 2017

      Glad you like it!

      If I understand your question, the TLF reactors are typical media reactors, with input and output connections on the top. The input connects to a tube that runs down the middle to the bottom, so the flow goes from bottom to top.

      The reactors are fed from a manifold that runs along the back of the top shelf, fed by a Mag 9.5 pump (950 gallons per hour, recently upgraded from a Mag 7) from the sump. There are pairs of valves, one pointing up and the other down, about every foot, to feed tanks, reactors, or whatever.

      Drainage is via a 2″ pipe that runs along the back of the bottom shelf to the sump. There are eight 2″ openings, about every 6″, to accommodate drain hoses from tanks and reactors.

      So, each reactor gets its input from the manifold, and empties into a 2″ drain hole to the sump.

      Because the pump feeds the whole system, rather than a single reactor, I can only guess at the flow rate into the reactors for now. The Mag pump nominally produces 950 gph, which is considerably reduced by turns through the chiller and manifold, and has about 4′ of head pressure getting up to the manifold. The valves to the reactors are wide open, and they are lower than the tanks, so I expect they are getting about 100-150 gph each. More would be better, and I am considering upgrading the return pump (again!).

      Let me know whether I answered the right question, or if the answer needs clarification.

  2. Reply
    susanne August 10, 2017

    Thank you, yes, that answers my question in wonderful detail. Shared sump, shared pump/flow and overall water.
    If and when I setup algae reactors, I plan on having them on a separate water cycle so that the nutrients only to the reactors, UV can be used to get the in this case unwanted minilife without getting either of those aspects involved with the slug/fish/whatever systems as I want to keep nutrients in check and planktonic life abundant for my filter feeders.
    The reason I ask about flow/water speed is that from my observation, bryopsis loves high flow (seems to grow best on outflow nozzles), yet this requires a bigger pump than I would want to involve in my normal tank as their inhabitants like flow, but not a giant sucking deathtrap.

    BTW, I love the manifold, drains, and rather flexible infrastructure to support your ever changing tank systems. I need a tank room 🙂

Leave a Reply

Your email address will not be published. Required fields are marked *