Dear Mr. Goemans:
For approximately eight months now in my reef tank I have rapidly growing forms of stringy globs of bubble filled goo on my live rock. It started shortly after a die-off of Derbesia. I thought it might be cyanobacteria, but after augmenting the aquarium with Boyd's Chemi-Clean, then trying UltraLife Red Slime Remover, neither product helped. I'm not sure what information you need to help diagnose this problem, so I'll give you what I can.
Aquarium: 75 gallon with 65 gallons bulk water. I have approximately two inches of CaribSea Seaflor Aragonite Reef Substrate and perform a two gallon water change weekly. There's a Berlin style sump with its sponge cleaned every 7 days. Also in the sump are three 300 micron media bags each containing 125 ml of Seachem SeaGel, and I alternate out the oldest media bag every 30 days. There's also one 150g media bag of TLF Phosban in a high flow area. There is a Marine Technical Concepts 4500S protein skimmer supplemented with an Aquarium Systems Sea Cyclone 150. According to your second booklet, Protein Skimming and Activated Carbon Secrets, the 4500S is operating just fine. The CPR over-flow is cleaned every seven days. Aquarium turnover rate is about ten times per hour, with a SCWD and two small powerheads making a mix between surge and turbulence water flow. There's approximately 100 pounds of live rock aquascaped in an island type formation with very open archways/overhangs and many places for the fish to swim through and hide if need be.
Lighting: There's a combination of HQI & powercompacts. The light fixture metal halide ballasts have been replaced with IceCap's 150 watt electronic ballast which powers two 14000K DE HQI lamps on for eight hours, with the two dual 420nm/460nm actinic lamps starting out the lighting cycle by being on for two hours before the MH's come, then five minutes later they go out, yet come back on five minutes before the MH's go out, then stay on for another two hours. But have now reduced it to only four hours of HM lighting.
Tank inhabitants: 3 Calcinus laevimanus crabs; 6 Astraea tectum, 1 Stomatella varia, 2 Turbo fluctuosa, 12 Ceriths (thank you for answering previous email regarding ceriths laying eggs), and 1 Astraea phoebia snails. As for fish, 1 Zebrasoma flavescens; 5 Chromis viridis; and 2 A. ocellaris. As for corals, 1 Montipora digitata; 1 Seriatopora hystrix; 1 Sinularia polydactyla; 1 Trachyphyllia geoffroyi, and possibly a dozen and a half blue and red mushrooms, 1 Cladiella sp., 1 Sarcophyton glaucum, 1 Heliopora coerulea, 1 Green Hairy Mushroom rock (Rhodactis indosinensis), and 1 Caulastrea furcata.
Water Quality: Water Temperature 76.6 to 77.8, S.G. 1.024, NH3 - 0: pH (Pinpoint Monitor): 8.15, NO2 - 0: Ca: 390 mg/L, NO3 - 0: Mg: 1150 to 1225 mg/L, PO4: less than 0.1 mg/L, Alkalinity: fairly stable at 3.5 meq/L, SiO2: less than 0.2, Iodide: 0.06 or 0.08, but color chart is hard to compare, Sr: between 6 and 8 mg/L. That's all I test.
Additives: Seachem Reef Advantage Magnesium, TLF Kalkwasser, Seachem Reef Advantage Calcium, Seachem Reef Builder, and Seachem Reef Iodide.
I have done everything shy of scrubbing the rock with white vinegar, and in fact I had a UV going for a few months but I noticed a dieback of copepods. I think, but am not 100% sure on this one, but after reading your booklet, going on saltcorner.com and numerous other general searches I believe this snot on my rocks is Prorocentrum sp.
First, let me thank you for an excellent letter, where two things standout! Your description of the "stringy globs of bubble filled goo," which are probably brown, and is no doubt a bad case of dinoflagellates alga that cause these gelatinous masses. It is usually introduced on a new piece of live rock or coral animal and can easily become problematic if the bulk water is rich in organic material, and I would think the condition after the hair algae died off, and the fact your bulk water is currently too high in phosphate, are the causes.
This is a free-swimming alga and is sometimes difficult to cure. A small microscope would help identify this alga; if the alga cell has a flagellum, i.e., a tail (for propelling itself through water), it is a dinoflagellate. If it does not have a tail, it's a diatom alga. Nevertheless, I don't think it a diatom since you use DI water, therefore your silica level, which encourages diatoms, is probably well under control. This leaves the dinoflagellates as the cause. Silicate is not one of its needs as is the case with diatoms. Unfortunately calcium carbonate is. Since we cannot rid the aquarium of its calcium carbonate content, its necessary to siphon as much of this pest alga and as often as possible to keep it minimized as much as possible. This alga can also be reduced/eliminated with the use of ozone or a UV sterilizer. Also helpful is flowing all aquarium water through a sponge filter, which should be cleaned twice a week. And yes, it may be a Prorocentrum species, such as P. arenarium. Yet even though a photosynthetic species, cutting back your light may only be a temporary help, and possibly impact some of your corals. I would go the road suggested above first before shorting your photoperiod.
Additionally, your phosphate is too high and a major contributor to this alga. It should be no higher than 0.015. Putting any PO4 remover in a bag and simply placing it where some water flows around it, does not suffice, even if it's in what you call a 'high flow' area. It needs to be in a canister filter or a phosphate reactor to do its job adequately, as water 'needs' to be forced 'through' it! Either add a reactor, or do what I do as follows;
I use a small Fluval canister filter, which has three internal baskets. I first filled the lower basket with activated carbon (I use either ESV or Boyd Chemi-Pure) in a sack of course, and I also cut up a Poly-Filter into small pieces (More areas of absorption that way). That fills the first basket. In the middle basket I place a layer of filter fluff and spread five tablespoons of ROWAphos or Warner Marine over the filter fluff. Then cover the media with another shallow layer of filter fluff. I do the same in the top basket and change the media when there is the first sign of any phosphate reading on my Salifert test kit.
I hope this helps, and keep me posted,