It has been quite some time since I have posted anything about Box of Slugs 2, the tank at home that is connected to a coral reef aquarium.  There has been a lot of excitement, such as the appearance of several species of Sacoglossans that had ridden in with live plants.  However, without large grazers such as urchins or snails, it has also been difficult to control the growth of algae, such that much of the tank was quite furry and subject to blooms of cyanobacteria (blue green algae, a.k.a. red slime).

The mass of hair algae may have had some benefits as food for growing Elysia, but it also created dead spots with poor circulation, and overwhelmed some of the desirable species of macroalgae.

After a few tweaks, and a little patience, the mass of filamentous algae has died back, and the macroalgae and seagrasses are thriving.  I got rid of the large rock that impeded flow, started dosing vinegar as a carbon source for the plants, and assembled a filter to remove debris and increase circulation.

The tank is looking pretty good at this point.  There is a variety of macroalgae (Penicillus, Udotea, Avrainvillea, Halimeda), along with some Bryopsis and turtle grass.  A few gorgonians add a little variety.  All the plant species seem to be growing well, and there is little sign of the plague algae coming back.

Box of Slugs 2, 8/29/15.

Floor of Box of Slugs 2, 8/29/15

Probably the most important change was the addition of this filter to increase circulation and remove some of the debris.  It consists of a sponge sleeve over a perforated 1″ PVC pipe, connected to an Eheim 1048  pump.

Sponge filter below surface, 8/29/15

The pump is stuck to the wall of the tank with a magnet.  The arrangement allows the pump to be partway out of the water to minimize heat transfer.  The output goes through a Hydor Flo rotating deflector, which provides circulation throughout the tank.

Eheim pump driving sponge filter. Note the output through the Flo deflector. The sponge to the right covers the drain that returns water to the sump, and is not part of the filter. 8/29/15

The resident slugs are three E. crispata.  I have decided to separate the larger Elysia species, with clarki in the hatchery at USG and crispata in BoS2.  Each system also has a few smaller hitchhiking species.  BoS2 has a few of the frilly presumed Cyerce, while BoS1 has some presumed E. papillosa.

The E. crispata seem quite happy, but are largely ignoring all of the macroalgae species in favor of a few small patches of Bryopsis.

E. crispata on Udotea, 8/29/15

E. crispata cruising Box of Slugs 2, 8/29/15