Dear Bob,  

Hope you can help. I have a 600l mixed reef that is running smoothly apart from what I can only describe as reef snot! I repeatedly get a covering of this mucus type stuff on several rocks. I have attached a photo, however it is a light brown in colour and occasionally forms bubbles. It is loosely attached and easily syphons out but generally regrows quite quickly within a couple of days; occasionally it may take a week to regrow, but always seems to come back. If left, it will grow into large globules and strings that sometimes detach in the flow. The problem started a couple of months back. 

Do you have any idea what it is and how i can get rid of it? I suspect it could be some kind of bacterial algae? 

Some info about my reef if it helps: It has been running approx 2 years and is a standard Berlin type system with mature rock. I utilise a good quality protein skimmer which is slightly oversized and iron based phosphate remover in a Deltec fluidiser. Flow is moderate to strong using Tunze streams. Magnesium, calcium and KH are kept in check with balling lite using Fauna Marin salts apart from KH for which I use standard bicarb of soda from the local cash and carry (£4 for 3kg!) 

Water parameters are good and stable with nitrate and phosphate being unreadable on Salifert test kit and a Hanna tester. I've attached a general photo of the tank for reference. 

Many thanks and best regards, 

           Ian, I have seen, even personally experienced this sort of light brown coloured slime issue'¦ and taken a look at bits of it through my handy dandy Mattel-Intel QX3 microscope.  As far as I can tell, most of the life here is/was Dinoflagellates'¦ single celled algae with whip-like and a girdling flagella (for locomotion)'¦  along with a mix of other algal groups members, Protists'¦  There are a few standard approaches to limiting such growth. These include nutrient limitation (through good skimming which you have, use of some chemical filtrants, water changes, gravel vacuuming, the use of in-place and remoted DSBs/Deep Sand Beds'¦) and nutrient introduction prevention (rinsing frozen/defrosted foods, using foodstuffs that are discrete and completely digestible and palatable so that they're consumed'¦). Importantly, attention to raised and sustained RedOx (covered in an article in this issue of UM,  do read this) perhaps through the introduction of Ozone, or other means e.g., increased pH, above 8.5 during the day,  low of 8.3 during the night. All these are activities that favour other organisms that will out-compete noisome algae for nutrients.

You mention the possibility that this mass is bacterial algae, likely referring to Cyanobacteria or Blue-green algae. Both Dinoflagellates and BGA are indeed slimy, and the latter does occur in several colours, though rarely brown. Determination of group can be readily determined by microscopic examination; the BGA being Monerans and like bacteria lacking nuclei and having but one circular strand of DNA.

You also note the age of the system and that it is well-established. I encourage you to either add, or renew some part of your live rock here'¦ this will add to RedOx, and replenish your likely depauperate mix of life on and in the rock and substrate.  The ecological improvement will also grant you relief from the brown slime problem.

The lack of detectable nitrate and phosphate are telling'¦ these nutrients may be being taken up by the undesirable biota here, or may be dangerously limited, otherwise unavailable to your purposeful livestock here. To put this bluntly, I would be pro-active in reducing, ridding your system of the brown slime.

Re: Live rocks turning dark greenish-black now sand covered by a greenish mat 4/19/10
Greetings ! O great knowledgeable ones,
<Where? They owe me money!>
About a month ago, I had mailed you regarding my rocks turning blackish green on me. Well now its the sand ! There is this mat of green algae-like stuff growing on the sand and on the rocks. It is cobweb like in structure.
Picture attached. Is this BGA ?
<Yep><<Mmm, maybe more Diatoms/Bacillariophyceans. RMF>>
Grows only in flow deficient places.
<Often the case.>
Should I reduce the photo period ?
<Light is not often the limiting factor for it's growth, phosphates and nitrates are bigger issues here.>
I employ a 20 gal monthly water change. pls do advice.
<More water changes.>
Also I noticed that there is no mention of Calcinus elegans in your hermit crab database. Wondering if it helps in the eradication of BGA.
<Of limited use here. See here and related FAQs for more http://www.wetwebmedia.com/bluegralgae.htm >
Thanks Blesson
<Welcome>
<Chris>

Re Mandarin hlth., was fat lip, now swollen pooter... Alpheid ID, Diatoms   3/11/10
Hey Bob,
Thanks for getting back to me so quickly.
The mandarin seems to be acting completely normal but his issue persists. I wanted to take this time to ask for some guidance on a few issues I'm having. I believe I told you that I recently down-sized from a 75 gallon to a red sea max 34 gallon all in one. I kept about 20 lbs. of live rock from the big tank and added to it about 25 lbs. of new live rock from the LFS. I also saved about 2 cups of sand from the big tank and added 20 lbs of black pacific reef sand to the new setup. I used 2-3 gallons of water from the big tank and added new RO/DI salt water in the new set up. Well the tank has been set up for a month now and I am pulling my hair out dealing with one issue after another. So I hope you can help with a few things because I'm losing faith in my ability to maintain my tank. So here is my current set up:
34 gallon red sea max all in one
20-24 lbs sand
45-50 lbs live rock
I replaced the regular carbon bag from this package with Chemi-pure elite and also added a bag of Seachem Purigen.
I am also running a Aquaripure nitrate filter.
I change 5-7 gallons of water about every two weeks, replace with RO/DI salt water and top off with RO/DI fresh water all bought at the LFS.
Livestock includes:
Mystery wrasse (moved from old set up)
Green mandarin (moved from old set up)
Yellow watchmen goby (added to new set up after 2 weeks)
Scarlet cleaner shrimp (moved from old set up)
pistol shrimp (added to new set up after 2 weeks)
pink tile sea star (added to new set up after 2 days but died after 2-3 weeks)
orange sun coral polyp frag
green starburst coral frag
green Zo frag
hermits
Astrea, Nassarius, and turbo snails
water parameters:
ph 8.3
nitrate 0-5ppm
nitrite 0
ammonia 0
calcium 420
<Magnesium? I would test for this...>
Alk 14dkh
I feed the fish frozen Mysis and brine shrimp, and blood worms all soaked in Selcon.
I feed the coral zooplankton or reef chili
I also dose with iodine, purple up, and Seachem liquid buffer as needed.
Alrighty then, I was wondering what species of pistol shrimp I picked up.
<... looks like an Alpheus sp., but I don't see it in my print ref.s or on the Net. There's summat similar on Keyscritters.com, but I don't see this listed elsewhere.>
I have been looking around online and have not found any that look like him. I bought him so that he might pair up with the goby but this doesn't seem like its going to happen
<And can even be dangerous. See today's "Daily FAQs">
and even wondered if he might be responsible for the goby's injury I noticed yesterday.
<Oh yes, could well be>
Secondly, I was hoping you could tell me what caused the sea star to perish.
<See WWM re... there is little hope for this Fromia>
He was in the new tank for nearly three weeks albeit he didn't move around too much and suddenly he has a hole in his disk and what I can only guess were his guts hanging out. And last, I have this reddish brown stuff growing all over the sand bed and the glass and a spot or two on the live rock. Is this Cyanobacteria or what?
<I think "what"... Diatoms likely. Do you have a microscope?>
I can clean off the glass or stir up a spot in the sand and within hours its back. I do water changes and as far as I know keep the water parameters in check so what could be causing this stuff to grow so fast?
<... again... learn to/use WWM:
http://wetwebmedia.com/dinoalgcontrmar.htm>
Well I'm sure you are tired of reading by now so I will post some pics for your viewing pleasure and I hope to hear back from you soon. Thanks again for all that you guys do...
Frank
<Wish I could be of more direct, complete help Frank. BobF>