Diatoms or Dinoflagellates ?

[S!mon]

I have a 4 year old reef (30 gal) that has had this brown slime algae for a little more than 1 year. It mainly grows on the sand bed and if I siphon the sand the brown slime returns the next day. My phos. reads 0 and if my trates get above 5, I do a 10 gal water change. I have reduced my photo period to 2 hours a day, and have tried complete blackout for 1 week. The week without light certainly helped, but I think my zoas and clams almost died from it. I'm thinking of giving away the corals and clams that have survived this and taking the lights off the tank for a month. Does anyone have a diffrent suggestion ? Thank you, Simon.

 

[Anonymous]

I wish I did, sorry. But, if I understand you, it's not really a problem anywhere else besides the sand bed, is that correct? Have you considered siphoning out the sand itself? I know it sounds weird but maybe it's acting as a sort of nutrient sink of sorts. I don't really know, it's a crazy thought, but if you're really considering dismantling the tank anyway it might be worth a try.

 

[trido]

How about regular WC's regardless of what your nitrate are reading?Maybe 20% a month like clockwork. Also is your skimmer truely adequate for your tank?

 

[Anonymous]

20% 1x/month won't really do anything. 25% 1x/week might be more like it, but even then it wouldn't put a dent in the numbers, it might just help it hold steady. What I'm thinking is that something is "fixing" the nitrate level, so when he tests he gets a lower reading. Plus, the sand may be holding a good bit of detritus, which is why I suggested just pulling the bulk of it out.

A few giant water changes might actually help, assuming that the source water is (relatively) nutrient-free.

 

[S!mon]

Sorry guys, it's been a crazy day at work! I normally do a 10 gal WC every other week. Going to a bare bottom is the last resort. I'm thinking of buying 2 over size power heads (Hydor #4 @1200gph), massive water changes, and lights off for one month.

 

[trido]

I'm thinking of buying 2 over size power heads (Hydor #4 @1200gph), massive water changes, and lights off for one month.

IMO thats a little extreme. Id bet the cyano would just come back after you resume your normal tank routine
Maybe a couple #2s or #3s. and a couple 50% WCs back to back. I wouldnt shut the lights down or get rid of the corals.
At four years old maybe it is time to suck some or most of that sand out of there.

 

[Anonymous]

Yeah, I'm putting bells on that, I agree with you.

 

[S!mon]

This stuff doesn't look like cyno, it is rust brown in color. I don't think its diatoms, but I'm not sure. It looks like pictures of dinos that I've seen online. Water movement in the tank is probably too low right now as I have one rio powerhead and my return. The sand in the tank is only 1.5 inches deep and about 2 years old. My skimmer is ok at best (thinking of the octopus NW)but it does produce skimmate. Maybe I should get a better skimmer coupled with 50% water changes for a couple of months? Thanks trido and seamaiden, I appreciate the help!

 

[Anonymous]

Do large water changes (50% minimum at a time), do them frequently, as outlined above. When you do them, vigorously vacuum about a third of the sandbed. It is definitely possible that the skimming could be an issue, and if you think the water movement isn't sufficient then it sure won't hurt. A lot of people worry about creating the toilet bowl effect, but ocean fishes (with the exception of some lagoonal species) can deal with fast rushing water and strong movement. That could help blow out collected detritus, as well as disallow settlement on the sandbed of whatever it is you may have (it's really hard to determine definitively in a lot of cases without an actual visual -- microscopic -- inspection of the substance).

Best of luck and you're welcome!

 

[Anonymous]

Oh yeah, cyanobacteria comes in a rainbow of colors, so don't rule it out based on coloration alone.

 

[S!mon]

I use a microscope every day at work, would it be worth taking in a sample of this stuff to try and determine what I'm dealing with ? (suddenly feels stupid for not thinking of this a year ago )

 

[trido]

Looking under the microspoe surely can thurt if you actually know what your looking at. I surely wouldnt. I wouldnt recommend get koralia #4s because I have two. One in my AGA 65 and one in my frag tank. At 1200GPH one alone causes the sand in my 65 to have a trough in front of it. Two in a 29G would be a literal sand snowstorm.
You could definatetly, without a doubt use alot more flow though.

 

[Anonymous]

I use a microscope every day at work, would it be worth taking in a sample of this stuff to try and determine what I'm dealing with ? (suddenly feels stupid for not thinking of this a year ago )

Yes! Don't feel too stupid. If you need to find examples, try writing Bob Fenner at wetwebmedia.com. If he doesn't have any photos on file he might likely know what direction to point you in.