Question about diatoms...

[Original Fin]

Went away for the weekend and returned to find my diamond goby dessicated on the floor in front of the DT. A little odd since he never ventured further than a couple inches off the bottom before. He must have been chased out by the bicolor angel. Well, next time I'll have to make some sort of egg crate shroud.
The only thing that changed for the tank when I was gone was that I wasn't there to feed it for a day and a half. I did use a feeding block though.

This goby was an essential tank janitor, and did a great job of keepping the top layer of substrate crystal clean. In the two days he's been gone, the sand bed is already beginning to crust over in places with diatoms. I won't be able to introduce another Goby for quite some time as my QT tank is occupied for the next month by two juvenile Occelaris Clowns.
Here's my question...will it hurt anything to just let the diatoms build up on the substrate surface? The only other detrivores I have in my tank right now is one hermit, a coral banded shrimp, and two nassarius snails. I have other species of snails as well, but they rarely go near the substrate. Will things ballance out on their own, or should I be looking for another method of controlling the diatoms? Tank is 14 weeks old.

55G w/ HOB protein skimmer, (no sump or additional filtration besides 60 lb LR, 50 lb LS) approx 1200gph flow. 216 watts T5HO...(2) 10K's run 10 hrs/day, (2) actincs run for 12. Corraline seems to have a pattern of advancing and receding on the LR...right now it's advancing more agressively than ever, and the first couple spots have just appeared on the back glass.

PH- 8.2-8.3
Temp- 79f
Ammonia-0
Nitrites-0
Nitrates-5
Calcium-440
Alk-2.8 meq/l
Phos- 0.1

[Ninong]

Diatoms won't hurt anything. If you want, add a Mexican turbo snail or two (Turbo fluctuosus). I would tell you to add a small fighting conch (Strombus alatus), but you shouldn't do that in anything less than a 90-gal tank, or thereabouts -- something with a lot of open sand bed.

Diatoms are perfectly natural in a reef tank but, if the water is good, they shouldn't be noticeable. If you have noticeable diatoms, it means you have excess silica in your water. Usually it comes from your source water -- the water you use to top off your tank and the water you use to make your saltwater.

Diatoms use silica to construct their cell walls. They cannot exist without silica. Once they exhaust the excess silica in the water, their population usually gets so low that you can't even see them. Maybe just a few here and there will be noticeable.

It's not a serious problem unless it gets to the point where you can't even see through the glass and you have to clean the tank daily just so you can see inside. A diatom concentration like that is usually only experienced during the initial tank cycle and it usually goes away in less than two weeks all on its own.

[Original Fin]

Diatoms won't hurt anything. If you want, add a Mexican turbo snail or two (Turbo fluctuosus). I would tell you to add a small fighting conch (Strombus alatus), but you shouldn't do that in anything less than a 90-gal tank, or thereabouts -- something with a lot of open sand bed.

Diatoms are perfectly natural in a reef tank but, if the water is good, they shouldn't be noticeable. If you have noticeable diatoms, it means you have excess silica in your water. Usually it comes from your source water -- the water you use to top off your tank and the water you use to make your saltwater.

Diatoms use silica to construct their cell walls. They cannot exist without silica. Once they exhaust the excess silica in the water, their population usually gets so low that you can't even see them. Maybe just a few here and there will be noticeable.

It's not a serious problem unless it gets to the point where you can't even see through the glass and you have to clean the tank daily just so you can see inside. A diatom concentration like that is usually only experienced during the initial tank cycle and it usually goes away in less than two weeks all on its own.

Thanks Ninong, you're the best. I've been feeling like I might have a problem with diatoms...as recently as last week I was needing to clean the front and sides every day. Something seems to be changing in the water chemistry though...all the hair algae went away two weeks ago, then this week, coraline has taken off and diatoms (at least on the glass) have slowed way down.
Mind if I ask another question? When I first set up this tank, I had a couple decorative rocks (for FW) in the tank. I took one out, and left one in because it happened to be the perfect size and shape to support part of the base of my rockwork. It's still in there...nothing grows on it, of course. Could this possibly be a source of silicates, and should it be removed?

[Ninong]

When I first set up this tank, I had a couple decorative rocks (for FW) in the tank. I took one out, and left one in because it happened to be the perfect size and shape to support part of the base of my rockwork. It's still in there...nothing grows on it, of course. Could this possibly be a source of silicates, and should it be removed?

I doubt it could be the problem. However, maybe you should take it out anyway? I wonder why nothing grows on it? That's odd. In my tank, coralline algae grew on everything. Absolutely everything.

[BubbaWPB]

Fin, sorry to hear your goby committed suicide.

Ninong, is that stuff on the sand diatoms or that slime algae stuff ("blue-green algae" that is never blue or green in a tank)? It's sorta hard to tell from what I can see...

Fin, how long has your tank been set up, by the way? Do you mix your own saltwater or do you get it at the LFS? If you mix your own, do you filter your water - RO, DI, or RO/DI?

[Original Fin]

Fin, sorry to hear your goby committed suicide.

Ninong, is that stuff on the sand diatoms or that slime algae stuff ("blue-green algae" that is never blue or green in a tank)? It's sorta hard to tell from what I can see...

Fin, how long has your tank been set up, by the way? Do you mix your own saltwater or do you get it at the LFS? If you mix your own, do you filter your water - RO, DI, or RO/DI?

Bubba-Tank's only been up for 14 weeks. I mix my own, and use RO/DI...thoughts?

[Ninong]

Ninong, is that stuff on the sand diatoms or that slime algae stuff ("blue-green algae" that is never blue or green in a tank)? It's sorta hard to tell from what I can see...

Bubba,

I'm accepting his description of it as diatoms because my eyesight is not very good at all, especially since my cataract surgery last November. The color is a little off for diatoms but that could be something to do with the picture. Diatoms are usually anything from a light golden brown to a dark brown.

"Blue-green algae" is a really dated description of cyanobacteria that is only used now by older botanists who are hardheaded. It has been classified as cyanobacteria, Kingdom Monera, for decades now. Ever since the invention of the electron microscope.

We don't have any of the "blue-green" stuff in our reef aquariums because we don't have that blue-green species of cyanobacteria in our reef aquariums. What we usually have are the reddish to very dark reddish cyanobacteria. I have no idea how many different species of cyanobacteria there are but it's probably in the thousands. Here's a taxonomy reference for cyanobacteria that goes back to 1977 but that's outdated now. They keep reworking it every few years. Anyway, it hasn't been classified as blue-green algae for more than 33 years, at least, but some people insist on keeping it in the plant kingdom. I really can't understand why it's still called blue-green algae by so many people in the business end of this hobby. I guess old habits die hard.

I think most of the cyanobacteria that we have to deal with in our reef tanks is the type that forms strands of cells that can be physically disrupted by strong water currents. I think you would call that colonial cells or something like that. Anyway, they look like long strands of cells under the microscope. The cyanobacteria that we run into is really not hard at all to deal with. I don't understand why some people have so much trouble with it. This topic has been the subject of exhaustive threads over the past ten years over at Reef Central. I think I have worn out my fingers posting stuff about cyanobacteria over there. After awhile you lose interest.

[Ninong]

I just checked something. I used the advanced search feature on the Reef Aquariums forum. I entered diatoms as the search term and Ninong as the User Name. It returned 62 different threads in which I have written about diatoms.

I did the same thing for cyanobacteria and got 73 threads in which I have posted about cyanobacteria over the years.

I think I have already answered every possible question on both of those topics to the best of my limited ability.

P.S. -- The only change in my opinion that I can think of is that I used to argue that controlling phosphate was not as important as controlling nitrogen in battling cyanobacteria. I later realized that even though nitrogen is its limiting nutrient in nature, phosphate is critical to one very important step in its photosynthesis. Therefore, reducing phosphate is just as important as reducing nitrogen (nitrate) in controlling cyanobacteria. So running an iron-based phosphate sponge will go a long way in controlling cyanobacteria.

I guess I should say that algae behaves a lot like cyanobacteria in some ways instead of the other way around. After all, it was cyanobacteria that got the ball rolling more than 3 billion years ago. We wouldn't be here without cyanobacteria. They invented photosynthesis by inventing chloroplasts. It was cyanobacteria that put the oxygen in Earth's atmosphere.

Phosphate is the limiting nutrient in freshwater lakes and nitrogen is the limiting nutrient in marine environments. Except that you can use phosphate to your advantage in controlling cyanobacteria because the cyanobacteria must have enough of it to go along with the nitrogen that is present or their photosynthesis will be limited.

[BubbaWPB]

Diatom blooms usually happen sooner and the RO/DI unit should do an excellent job at getting out any silica, phosphate, or nitrate from your source water. That narrows it down a bit.

In the short run - water changes will help and/or use phosphate binders. You might also keep an eye on how much you're feeding and what type of food. After 14 weeks, your tank should be done cycling - so next most common cause of detectible nitrates and phosphates is overfeeding. Don't starve the kids, but you might want to cut back on portion size...

In the long term you might want to give thought to increasing your bio-filtration if portion control doesn't work... or you could do a search on Reefland and follow Ninong's sage advice on dealing with Cyanobacteria and diatoms.

Note to Ninong - Bubba still uses "coelenterates" too...

[Ninong]

Yeah, coelenterate is no longer a valid description but it was used in some of the books that I read ten years ago. Blue-green algae was dropped decades ago but it's still in use. Most LFS people still call cyanobacteria "red slime algae."

[Jai1985]

quick question ninong.... i used silica play sand (washed many many times) in my tank...havent had much problem with anything...yes i have diatoms but i wouldnt call it outrageous...plus cleaning crew takes care of most of it....could this be part of the problem...???

[Ninong]

Probably not, especially if you rinsed it.