diatom bloom. how to get rid of it
 

12 week cycled tank. i just a new rock like 2 weeks ago and it got covered in diatoms. now my sand is covered and a couple rocks are covered. what can clean the sand? i have a bunch of nas. snails and cerith snails that do nothing. i have a brittle star who was supposed to help but hangs out in the rock. i cant get a goby because my blenny will attack it. i have a 30gal tank. doing 10-20% water changes every week.

time, things in a reef tank don't happen overnight. They are part of the natural cycling process

nikon is right...time.
Also, diatoms are an indicator of high Nitrates and/or Phosphates. What are you using for source water? Reverse osmosis/deionized water is your best, though fairly expensive to purchase a RO/DI unit, it will save you money and headaches in the long run.
Besides water quality, protein skimming and kalkwasser dripping will help your water quality and combat the diatoms. They will go away eventually.
Good circulation is also important so that there are no dead spots in the tank. You can blow some of them off the rocks with a turkey baster.

yes im using RO water and im tryint to get my skimmer working and it will be up in a couple days. I know this stuff takes time but how long? My corals seem to not open as much because diatoms are growing on the base. Nitrates/Phosphates are 0 and idk what kalkwasser dripping is. I try to suck up as much as i cant when i do water changes.

if your tank is new and still cycling you definately should not have any corals in the tank, i would take them back to the place you bought them ASAP

its not cycling, the tank is about 2-3 months old. It whent through all the cycles and it was stable for a good month but now its going through a bloom. My corals arent dieing, there just not opening as much.

So you're running without a skimmer at the moment?

Where are your nitrates and phosphates?

2 to 3 months is still a rather new setup, so I agree with what the others are saying.

nitrates and phosphates-0 but that could mean algae is taking it as soon as its introduced. Yes, im running without a skimmer but i have 45lbs of LR in a small tank which didnt even need a skimmer in the first place. Im pretty sure i dont overfeed. I know my tank isnt "fully cycled" but its cycled enough to introduce corals/fish. I think its just a small bloom on the rock but is there any type of animal that eats this stuff on the sand? Its really getting all over it and none of the animals that are supposed to stir the sand are doing the job. And once again, i cant add a goby.

For the LR, maybe a Turbo or two? I don't like the Turbo snails personally, they tend to knock things around. If you have things pretty secure, they might work for you on a temporary basis. For the sand bed, maybe a sand sifting starfish? They are pretty big though. I don't think they'll eat the stuff, but at least churn everything up a bit.

Cody

if it's a diatom bloom and not cyanobacteria, then your tank is still cycling

I think it's still too early for a sand-sifting starfish. It will eat everything it can find in the sand bed, then starve to death. The heavy predation will reduce the effectiveness of your sand bed, then the corpse will produce a bunch of nitrates. Give the sand bed some more time before you add any "sand sifters", whether starfish, sea cucumbers, gobies, or blennies*.

For churning the sand, I recommend nassarius snails. They rest in the sand but come out to find food, so they're not dependent on the inhabitants of the sad bed for their diet.

Pistol shrimp and goby pairs also keep the sand stirred up, but some people get upset when they start bulldozing the tank. Rock piles can be disturbed if they're resting on the sand instead of the glass. Small frags may occasionally wind up deep inside a tunnel, propping up the wall, especially if they were sitting on the sand bed. Even snails are not immune. Not only do their shells make good tunnel supports, but the meat inside is tasty, too. Despite all that, pistol/goby pairs are still great fun to watch.

What kind of blenny do you have? I'm no expert, but I believe many blennies and gobies can coexist. They look similar to us, but I don't know if they look similar enough to each other to stir up the kind of aggression that two gobies or two blennies would cause.

* Note - This specifically refers to "sand sifting blennies"/"sand sifting gobies". Many Gobies and blennies do not rely on sand bed critters for food, and don't require the same waiting time.

i have a starry blenny that has killed a ygc

most tanks under 3months will get a diatom bloom.....no lights for 3 days and it should burn out....if persistant than check your RO water supply

lawnmore bleeny will take care of it in 3 days, and don't forget your water change.

Re: diatom bloom. how to get rid of it
 

try nassairus snails

like others said, just give it some time. most of my tanks went through periodic diatom blooms for the first couple of months, even after the tank was cycled. sure some snails and hermits or fish might eat some of the diatoms, but the diatoms will wither away on its own. good luck

Same problem
 

I have a 120 gallon reef, about 5 month old. There was no algae problems and now my sandbed looks terrible. It is not cyano for sure, just some brown and green algae. I kept my lights off for 2 days, it helped. My phosphates are 0 and nitrates are less than 5. Not sure what else to do.

Goncharkina, if you have algae growth, you are getting a false phosphate negative. The algae uptakes the phosphate before you can measure it. Unless you are using a photometer such as hannah checker's phosphate or phosphorous, the low readings don't mean much. API and such are notorious for having poor low end readings.

You'd need to verify you follow the standard procedures for low phosphates. IE rinsing food, RO/DI water, etc. Lighting period can also affect it. Are you running an ATS (algae turf scrubber) or gfo?

Did you have corals in the tank? Does turning the lights off for two days affect the coral?

You can do a 3 day blackout with coral, just leave tank lights off. What kind of rock /sand did you start the tank with? If it was live, was it live in a bag, live from a tank running at your LFS, live shipped rock, etc. Sand and rock depending on various factors can leech po4, silicates for a year or longer. I know i've looked at a few threads on here in the last few weeks were people were having diatom blooms 14 months after there tank was setup. There really isn't an easy fix. As long as your not contributing to the problem by using tap water, over feeding, forgetting w/c's etc, it will eventually go away.

Edit: Also what lighting are you using? I had some par 38 chinese LED lights on my 55, and whatever spektrum it was, the diatoms loved it. Stopped using those lights and had no problems afterwards.