After three weeks of treating the Shrimphaus with Tetra AlguMin in an attempt at chemical control of black beard algae, I can confidently report that monolinuron, the active ingredient in AlguMin, has absolutely no effect whatsoever on black beard algae (BBA, black brush algae). The algae is as healthy and bushy as ever, does not scrub off even with vigorous rubbing, and may even have grown a little thicker. I can’t really tell whether monolinuron was effective against green algae, as that wasn’t a major problem and so I wasn’t paying careful attention. Certainly there was no visible green algae at the end of the treatment but there may not have been much in the first instance.
Black beard algae (BBA, brush algae) used to be a bit of a nuisance in the Fireplace Aquarium, but since switching to a high phosphate, estimative index dosing regimen, BBA and really all forms of algae have been pretty much a non-issue. Tanks need to sort their own equilibrium, and what works for the high-tech CO2-injected Fireplace Aquarium is not necessarily appropriate for the low tech Shrimphaus. In general I prefer to ‘live and let live’ within reason for algae in an aquarium but in the Shrimphaus BBA has got to the point where it’s hurting the plants and not looking very pretty either.
What to do about it?
It’s been more than four months since the Alternanthera reineckii ‘Rosanervig’ got planted in the Fireplace Aquarium, and whilst it seemed to be doing well initially, after 11 weeks things weren’t looking so great. I thought lack of light from overgrowing Bucephalandra caterina might have been contributory, so I did a massive epiphyte trim to restore light to most of the tank. That had very positive effects on the Cryptocoryne wendtii ‘Flamingo’ but didn’t really improve the alternanthera. There were floating fragments of what looked like otherwise healthy Rosanervig leaves and I have from time to time noticed some suspicious interest in the alternanthera from the amano shrimp. Some surveys of the interwebs suggests that amano shrimp eating alternanthera species is a known thing which could explain the observed damage.
As an experiment, I have shielded the top of one of the Alternanthera stems inside a mesh bag. The aquarium denisens haven’t particularly noticed, although I did see a cheeky amano shrimp sitting on the bag – it scampered when I tried to take its picture. We’ll do an updated report after a while to see how the bagged plant compares to its non-bagged counterparts.
Two week update: shrimp-proof bag fail
Well… it seemed like a good idea anyway. Whilst the shrimp-proof bag did keep the shrimp away from the alternanthera, the bag became a major breeding substrate for black beard algae and the plant inside the bag with no meaningful flow and no access to a cleaning crew did not thrive. Not only that, but I couldn’t get the bag off and wound up tearing the head off the plant in the process! Looking at it after the fact showed a few new leaves had sprouted so the plant was giving it a try.
That being said, in the ensuing carnage I did notice there was an alternanthera plant not in the bag that seems to be doing reasonably well, so I moved that over to the front of the aquarium and we’ll see how that does.