Brown growth on the Sand, Trouble Brewing?

[All__talk]

I’ve got some brown growth on my sand, it started in one small area that probably has the lowest flow in the tank and has slowly spread over most of the tank. It only grows in the light, none behind the rock work or where it’s shaded. I creates a crust on the sand, I vacuum the sand bed weekly with my water change and over the week it slowly comes back. It seems like it might be nutrient based or at least assisted. Once it had spread to most of the tank a couple of weeks ago I cut back on the feeding to see if it would respond, and it has, the growth I’ve gotten in the five days since my last water change I was seeing in a day or two. I know my nutrients are lower because my Chaeto growth has slowed to a crawl. But now I noticed there seems to be a film growing on some of the rocks. I would really like to get a handle on this before it gets out of control. I have included some pics below in the hopes someone can identify it. It is darker and there is more of it than the pics show.

One thing I just realized today, the problem may have started about the same time I switched from regular Instant Ocean salt to IO Reef Crystals. I switched because my Magnesium was running a little lower than I’d like and the RC salt did boost it. I’m out of salt now so I’m going to switch back to IO and see if it helps.

I also have something brown and slimy growing in my sump but it seems to be different, it comes and goes with the light cycle (opposite of the DT). By the time the sump light comes on at night its almost gone, then in the morning when the light goes out its everywhere. I’ll get some pic and add more detail about it tomorrow.

System Info…
46G Bowfront, 25G sump/fruge, two Korilla 3s, Mag 7 return, Aquamedic skimmer, PC 96watt lighting (x2), one 10k, one actinic, DI/RO filter – TDS=0.

Current inhabitants: Coral Beauty Angle, Ocellaris Clown, Three Stripe Damsel, Long Tentacle Plate Coral, Ricordia, Zoas, Yellow polyps and some snails.

All fish and corals seem to be doing well. I drip Kalk for all my makeup water. I do a 5G water change weekly. I test my parameters weekly and they have been consistent for months… as of 7:00pm tonight.
SG= 1.025, Temp = 79F, PH= 8.4, Am=0, Ni=0, Ca=460, KH=9, Po=0, Mg=1425

http://img.photobucket.com/albums/v204/All_talk/Aquarium/P3040455.jpg

http://img.photobucket.com/albums/v204/All_talk/Aquarium/P3040451.jpg

http://img.photobucket.com/albums/v204/All_talk/Aquarium/P3040457.jpg

Gary

[returnofsid]

Typical diatom algae. It's part of every new aquarium. It'll also bloom anytime there's a large change, or sand is heavily disturbed. Nothing to worry about.

A piece of advice, that will help. Stop vacuuming your sand bed. This is probably why it keeps spreading. ANY Disturbance of the sand bed will cause it. Sand beds should be left alone. Actually, WE should leave them alone and have critters that keep them stirred up, such as Nassarius snails.

Your description of what's going on in the sump sounds troubling. Does it look like SNOT? The description of coming and going, with your light cycle is the trouble part. Look up "dinoflagellates." Sounds just as your describing. Problem is, when lights go out, it starts dying. When it starts dying, it takes all the oxygen in the water with it. It's also toxic to herbivores that eat it.

[All__talk]

I did a lot of searching yesterday and diatom algae was one of the suspects. The tank is not really that new, I’ve had it for over 4 months but it was up and running for more than 2 years when I bought it. There was a little mini cycle when I moved it with slightly elevated Am and Ni numbers but settled down within a month or so. But, I have been hitting the sand bed pretty hard with the vacuum during the last few water changes thinking it might help, looks like that was a mistake, it did seem to make it spread. I’ll leave it be for a while and see how it goes. I’ve got 7 Nassarius snails now (assuming they as all still alive), I see them mostly at night and their tracks in the morning, should I add more? What other critters would be good to mix up the sand? I had an Orange Spot Goby, he was pretty good at moving sand around, but he decided to try surfing the hardwood floor, didn’t work out so well for him. :(

Here are some pics of the sump, the first is just as the light comes on and you can see some small spots of the brown goo. The second pic was taken this morning after about 9 hours of light. I did notice last night after about 2 hours of light it looked about the same as it did this morning, so it seems to come up pretty quick with the light. It’s not really slimy, more like mold. You can see in the pic that the top rock has less than other places. Most of it started there but about a week ago I brushed that rock off to see how it would respond. The growth brushed off very easy and drifted deeper in the sump. As you can see it has continued to grow where it fell but the top rock has stayed pretty clean. I’m planning on giving the sump a good clean out this weekend, suck out the detritus, brush/rinse the rock in a bucket and such. Then maybe go lights out on the sump for a few days?

http://img.photobucket.com/albums/v204/All_talk/Aquarium/3040450x.jpg

http://img.photobucket.com/albums/v204/All_talk/Aquarium/3040451x.jpg

Gary

[tangtang clown]

I have the same on my sand, only where my MH shines. I have 3 250w MHs installed over my 125 and the 2 end ballasts crapped out. The diatoms are only on the sand in the middle of the tank where the lights shines. I just installed the other 2 new lumatek ballasts last night and I will wait and see if it spreads across the whole sandbed. About 6 months ago I upgraded from a 75 to this 125. I moved everything over and the tank has never had MHs. I also use cheap Plusrite MH bulbs. May try upgrading the bulbs in the future. I will try to get some pics for you to compare.