Saltcorner
By Bob Goemans
By Bob Goemans
Dear Bob,
My company maintains a lot of large beautiful reef aquaria. We run all our tanks at between 70 and 80 degrees F, specific gravity 1.023, and pH 8.2. Our calcium levels are maintained at 400 - 450 ppm, and we use SpectraPure reverse osmosis and deionizing equipment to generate all of our water (Instant Ocean is our salt mix).
Sometime in the last few months we have had a couple of troubling changes occur. In one of our aquaria (a 300-gallon reef), we had a large population of the red planarians, and that has subsided a bit, but now many of our soft corals in the tank are not opening fully (although the clams are fine!). The first coral to suffer was the pulsing Xenia, which proceeded to shrink as well as cease to open. The lights on the tank are 250 watt metal halides, which are changed yearly. I also notice that since the planarians are still on the live rock (kind of carpeting it), I don't see a lot of coralline algae. The water flow is strong in this tank, powered by 2 pumps and circulated by 4 other pumps (I don't have their flow rates with me, but we aim for at least 10 x the volume of the tank per hour).
The other tank I am concerned about is a 75-gallon reef. This one is powered by a Rio 2500 pump, and has two 96 watt compact fluorescent bulbs (50/50) over it. This tank has a new kind of algae for us, which at first we thought might be dinoflagellates. It is reddish and smeary, but holds oxygen in little bubbles above it. It's not as brown as the dinoflagellates I have seen, though, and the "strings" holding the bubbles are not very long at all. Also, although it grows quickly, we aren't seeing the explosive growth I have seen in the past with dinoflagellates.
We are accustomed to "re-doing" of our tanks about once a year, meaning we rinse out the aragonite, plenum, scrape algae off the walls in the filter - basically an overall big cleaning to take care of pockets where the pumps don't circulate and manage nuisance algae (hair, slime) that tend to build up over time. Until recently, our strategies had worked pretty well, but I'm mystified by the recent events in these two tanks. Can you think of anything we're not doing that we should? And I would love your opinion on the new algae.
As always, thank you so much for your help.
Sincerely,
Karen Pianka
Hi Karen,
As for the first problem, it seems I've received at least four letters within the last month noting the same problem. Here's what each has been told:
Mushroom and leather corals seem to be a favorite gathering place. These flat worms are thought to be mostly harmless (Sprung, 2000), yet unsightly. When in great numbers they can block light from reaching photosynthetic animals. And some flat worms will consume both tissue and zooxanthellae and the corals may exhibit thin lines of dead tissue. I don't know if some corals are damaged to the point where they can't return to full health, however, most seem to slowly get better when the infestation is cleared up.
When there is an abundance of these flat worms, and if possible, remove the infected specimen and give it a five to ten second freshwater dip. Almost all the flatworms will drop off and any remaining can be gently brushed off. Of course not all corals can withstand a freshwater dip, but leather and mushrooms do handle it quite well.
Keep in mind these flat worms are photosynthetic and are attracted to light. Placing a lamp near the aquarium side panel at night will attract them in huge numbers making it easy to siphon out the majority very early in the morning. The reduced number my give other biological control methods a better chance at bringing their numbers under control.
As for a natural biological approach, the Palauan Banded Goby, Amblygobius phalaena, is said to eat the flatworm Convolutriloba retrogemma. Also, Wrasses, e.g., the Sixline Wrasse, Pseudocheilinus hexataenia, and Mandarin fish (Synchiropus splendidus) have cleared up the problem in some of my past reef systems. Also, the Sea Slug/Nudibranch 'Chelidonura varians,' (available at All Seas Fisheries in Miami/LA, and maybe Quality Marine and Sea Dwelling Creatures in LA) a black with two blue lines on the sides and two tail-like projections on the rear, is an efficient consumer of this pest. Also the scooter blenny, hawkfish and leopard wrasse (Macropharyngodon meleagris) may also consume them.
There is also some thought that the over use of iodine supplements, which flat worms concentrate in their internal fluids, may lend itself to their proliferation.
And caution, as there is some thought that killing them in large numbers with a chemical treatment of some kind could present a serious environmental hazard in the aquarium for all inhabitants. That's because their degradation could cause a large reduction of dissolved oxygen and/or since they are thought to harbor iodine in their tissues, the system may become overdosed.
Using the light/siphon out method has worked for the majority of aquarists having this problem. And having a few predators of these worms in the aquarium is a good back-up!
As for the brown algae problem, it would be wise to first see if its really caused by dinoflagellate. Use a small microscope, as that would help identify which form of brown algae is in the aquarium. If the alga cell has a flagellum, i.e., a tail (for propelling itself through water), it is a dinoflagellate. If so, it can be reduced/eliminated with the use of ozone or a UV sterilizer. Also, flowing all aquarium water through a sponge filter, which should be cleaned twice a week, is also helpful. Improving water quality is also helpful, if high in organic matter. If it's a diatom algae, then reducing silica is the way to go, and I would make sure the cartridges in your RO/DI equipment are still in good working condition.
If this doesn't help, there's an 'Algae page' on my website that contains photos of about 150 species of algae (good and bad) plus at least 60 known biological control species (fish and inverts) with the control species cross-referenced to the unwanted species of algae. Check it out.
And one last thing, hopefully you're not disturbing your plenum yearly, as that simply interrupts its efficiency. In fact, just heard from a person who has had his plenum system going for 12 years, and the whole system is still doing great.
Hope this helps,
Bob
