Diatoms? Dinoflagellates?  9/5/07
My aquarium is 4 months old. The regular diatom bloom during cycling is under control on the rocks, sand & glass, thanks to time, snails and hermits. However, I have a rusty brown algae covering the water surface.
<This sounds like Dinoflagellates.> <<Mmm, and/or Diatoms. RMF>>
What is it and how do I get rid of it?
<If this is D. then keeping the tank in the dark for a few days should just about wipe them out. Of course, being able to treat the tank this way is a luxury you have for being patient and waiting before adding any corals. :-) If this doesn't work, your best chance is to just keep manually removing the stuff. Running carbon (and maybe even a diatom filter) might help some. But with any luck, the few days in darkness should do it. Do a big water change after these few days to help remove whatever nastiness the D. may have left behind.>
I don't have fish or corals in this tank yet, and didn't know if this would be dangerous for these critters.
<It shouldn't be too dangerous for the fish, but D. can be quite toxic to corals and other inverts.>
Thank you for all of your help, past, present and future.
<De nada,
Sara M.>

Lots and Lots of Algae – 08/31/07 You guys did such a great job identifying our peanut worm, would you mind taking a look at our algae? I've been trying to identify it in the invertebrates book with mixed success. I've included four photographs of the ones I'm having trouble figuring out: <Ahh, I see them> 1) In the first picture, algae1, there is something I think is red bubble algae, but to the right, there is also something purple and furry that I have no idea what it is. <Mmm, might be a Red/Rhodophyte of some sort, but likely a BGA> 2) In algae2, our LFS told us the salmon-colored thing is an encrusting coral, but there are also two weird algaes there: one that you can see trailing from the left side of the rock on the empty spaces the coral hasn't covered yet, like wet purple yarn. The other, it's not very clear in the picture but the bulbous green thing in the foreground isn't just green algae sitting on a rock, it's almost like a balloon of algae floating around anchored to the rock. What on earth could that be? <Maybe Valonia...> 3) In algae3, I *think* the pink stuff in the upper left hand corner looks more like a sponge than algae when I look it up in the book, because it's covered with a film with holes in it. But what is that weird pink and green growth in the foreground? <Too blurry... maybe a sponge> 4) Sorry about the picture quality in algae4. They are magenta colored and shaped sort of like flower petals. <Yes...> 5) It didn't show up in the pictures but we also have these weird *long* string like things attached to our rock, looking like green fishing line. My husband thinks they're spaghetti worms but they don't look like the ones in the book. Any ideas? <... many possibilities> Thanks in advance for any light you can shed. I hope none of this stuff is toxic or anything. We also have that rusty brown crud that keeps growing back on our live sand, which I'm pretty sure is diatoms. <That and/or maybe more Cyanobacteria> It's kind of confusing though because we've had the aquarium for a couple of months now, and reading through the diatoms FAQ it seems like diatom blooms are supposed to be something that happen when you're just establishing your tank and then fade away. <Generally so, yes> Our brown crud has only just started growing recently. Is this a warning sign? <Mmm, perhaps... but not necessarily... could be just transient opportunistic species...> Our water quality is excellent, but lately I've noticed that our protein skimmer doesn't seem to be skimming as much stuff out. <Mmm, do give this a scrub and rinse...> Laura <And do keep learning, enjoying the process! What a planet eh? I'm not leaving! Bob Fenner>

Coralline Algae Growth, ID ?? 8/29/07
Hi! Hopefully you can help me.
<I'll give it my best.>
I have a 55 gallon tank with approx 45 lbs of LR. It has been running for almost 2 yrs. and recently I noticed a growth on the underside of one of my rocks. It appears to be a very hard substance, textured with ridges and lines, and dark brownish-green in color. (The texture reminds me of a brain coral.) It has grown in size over the past few months but has not yet moved to any other LR. The condition of my water has been great with no changes in nitrites, nitrates, etc. I know it is difficult to guess what this is without a picture (couldn't take a picture due to location of the growth), but I was hoping you could give me some suggestions of things it could be. That way I could research on my own and hopefully figure this out!
<Well, as you mention, it is difficult to give you an accurate ID of the growth without a pic, but I'm guessing it probably is a Peyssonnelia sp. of coralline. Do look at the picture here and see if it is similar to what you describe.
http://www.wetwebmedia.com/corallinealg.htm James (Salty Dog)>