disappearing diatoms...at night

[Duane Clark]

I've seen a few mentions of this on other forums (with no real explanation) but just a quick observation that while I am fighting a small bout of diatoms, I notice they completely disappear on the gravel when the lights go off. As they ramp back up in the morning they slowly return. (seems like a good way to tell the difference between diatoms and cyano). What is the explanation for this?

 

[Brew12]

I've seen a few mentions of this on other forums (with no real explanation) but just a quick observation that while I am fighting a small bout of diatoms, I notice they completely disappear on the gravel when the lights go off. As they ramp back up in the morning they slowly return. (seems like a good way to tell the difference between diatoms and cyano). What is the explanation for this?

Diatoms are photosynthetic. We often don't think of them in those terms, but they are.

 

[Brew12]

And don't fight your diatoms, enjoy them! They will be gone soon enough. They are just consuming the free silicates in your system and when those are gone the diatoms will go away, too.

 

[Duane Clark]

And don't fight your diatoms, enjoy them! They will be gone soon enough. They are just consuming the free silicates in your system and when those are gone the diatoms will go away, too.

Ha thanks. not really fighting them. just really managing them until they fade away. regarding the photosynthetic nature...that's true but so is algae and it doesn't disappear at night. It just seems like a strange occurrence.

 

[Brew12]

Ha thanks. not really fighting them. just really managing them until they fade away. regarding the photosynthetic nature...that's true but so is algae and it doesn't disappear at night. It just seems like a strange occurrence.

That has more to do with the cell structure than anything else. Some Dinoflagellate strains also disappear when the lights go out and come back when back on. Most macro algae has a fiberous structure that dino's and diatoms lack.

 

[Duane Clark]

so for some cases would this observation help identify a diatom vs cyano outbreak? I see where quite a few folks struggle with that.

 

[Brew12]

so for some cases would this observation help identify a diatom vs cyano outbreak? I see where quite a few folks struggle with that.

Maybe. There are also strains of cyano that will die off at night.

Diatoms are normally fairly easy to identify. It is a brown, powdery microalgae that you can blow off with a syringe. Cyano tends to form slimy mats.

 

[mcarroll]

I'm not sure that diatoms exhibit that behavior (they may), but dinoflagellates most certainly do. All of them (including cyano) can be considerd common in new tanks, depending on the phase you're in.

How old is your tank?

And what are you doing to manage them?

If you don't have a microscope, I'd highly recommend one – it sounds like you'd really enjoy having one! No need to spend more than $10 to get a (really) basic model. That's what lots of folks are doing these days!

Check this out: Selecting a microscope

(I have the toy scope myself...works fine! ...still deciding what to upgrade to.)

 

[Duane Clark]

I'm not sure that diatoms exhibit that behavior (they may), but dinoflagellates most certainly do. All of them (including cyano) can be considerd common in new tanks, depending on the phase you're in.

How old is your tank?

And what are you doing to manage them?

If you don't have a microscope, I'd highly recommend one – it sounds like you'd really enjoy having one! No need to spend more than $10 to get a (really) basic model. That's what lots of folks are doing these days!

Check this out: Selecting a microscope

(I have the toy scope myself...works fine! ...still deciding what to upgrade to.)

You could be right. I don't see any strings and no bubbles and my snails etc have not died from eating it. coral also look very healthy. You may be right about getting a microscope. I would enjoy that. man I hope it's not dyno. to answer your questions though:

1. the tank is just over 2 months old
2. I'm currently just performing regular weekly water changes and filtering with carbon and GFO. nitrates are around 5, nitrites and ammonia 0 and phosphates are best I can tell using my salifert test kit are below .03.

I only have coral and my clean up crew. I am planning in adding 2 sexy shrimp soon. I should also at this is a very small 14g nano.

 

[mcarroll]

I'm currently just performing regular weekly water changes and filtering with carbon and GFO

GFO can definitely encourage dino's to form in a tank this new. The problem is that you're very likely to be starving your microbial population (good and bad) for phosphate. The good guys seem to die off quietly. Things like dino's and some other algae have a more aggressive plan for survival that can take down a whole ecosystem even in the wild.

So discontinue your GFO immediately, IMO.

I'd also go easy on the water changes from here out. My rule of thumb at that stage of my tank was only to do them when nutrients or chemistry (ca, alk, mg) would dictate. In your case, using them to assist with manually removing some of this algae would be OK too.

Since everything is apparently still doing well, see if this makes the slime disappear. Give it a few weeks to work unless things get worse.

You should also see those nitrates being used up by your corals or some algae as things progress too.

If nitrates still aren't being used up and the slime keeps hanging around (or gets worse), then your system is definitely phosphate limited and you will want to consider some phosphate fertilizer to reverse the effects and get the nutrients in there a little more balanced.

(I hope it's not dino's too.)

 

[Duane Clark]

then your system is definitely phosphate limited and you will want to consider some phosphate fertilizer to reverse the effects and get the nutrients in there a little more balanced.

thanks so much wow...this is so opposite of what I thought it should be. I thought phosphate was the devil.

 

[mcarroll]

I thought phosphate was the devil.

You are not alone!

(You can go through the articles in the Nutrients section on my blog for lots of interesting research that I've saved on the topic, but even better....)

@Randy Holmes-Farley (our resident PO4-specialist) Have you ever written an article on how PO4 is not the devil....or have one to recommend if there are more than one?

 

[Brew12]

I wouldn't run GFO unless my PO4 is over 0.2ppm. I believe @mcarroll has a link that shows coral growth can start to be slowed when it is above that level.
I wiped my tank once because I ran too much GFO thinking that it was necessary. I learned.

 

[Duane Clark]

I also should note I have been using distilled water from Walmart for my ATO and saltwater mix. I don't have a TDS meter to know dissolved solids in the distilled but I assume(d) it was low to zero. Does not matter now I suppose as I just finished installing an RO/DI unit. what a pain in the **** but hopefully worth it.

 

[mcarroll]

hopefully worth it.

The water is soooooo cheap that the answer will probably still be "yes" even if it's a major pain every time you replace the filters.

(Try not to let that be a pain tho.)

 

[clockman]

I know this is an old thread, but I was looking for info on whether diatoms disappear at night and reappear in the day. So far, my only point of reference is dinos which I have battled a while back which appeared to behave in a similar fashion (ostreopsis). Well, I looked under the microscope and they appeared to be brown and flat like a disc which is unlike the ostreopsis which were more clumped and abundant. Can identify/confirm that these are the less problematic diatoms rather than dinos? (Sorry for the shaky video and poor pics). If they are diatoms, how is the best approach? Nothing really has changed since a tank crash a few months ago due to a heater malfunction (cooked the tank to 94F) which actually killed off the dinos which I was having an issue with at that time (2nd battle with them). Killed off most of my coral and bloodred shrimp as well. Thankfully all the fish survived.

 

[clockman]

One thought is that perhaps the increase in temp to 94F from the heater malfunction increased the silicates in the water column from the rock and substrate causing the diatom bloom?

 

[Dan_P]

I've seen a few mentions of this on other forums (with no real explanation) but just a quick observation that while I am fighting a small bout of diatoms, I notice they completely disappear on the gravel when the lights go off. As they ramp back up in the morning they slowly return. (seems like a good way to tell the difference between diatoms and cyano). What is the explanation for this?

Here are some thoughts on photosynthetic organisms disappearing.

Shading. Photosynthetic organisms cannot readily turn off photosynthesis if they are getting too much light. For mobile organisms, like cyanobacteria, diatoms and dinoflagellates, they move into the substrate. This can happen towards the end of the day when nitrogen and possibly phosphate become locally depleted. Fixed algae cannot shade and can be damaged.

Avoiding predation. By moving into the sand, microorganisms avoid night time predation.

 

[Deep]

Here are some thoughts on photosynthetic organisms disappearing.

Shading. Photosynthetic organisms cannot readily turn off photosynthesis if they are getting too much light. For mobile organisms, like cyanobacteria, diatoms and dinoflagellates, they move into the substrate. This can happen towards the end of the day when nitrogen and possibly phosphate become locally depleted. Fixed algae cannot shade and can be damaged.

Avoiding predation. By moving into the sand, microorganisms avoid night time predation.

is this always the case? I have a bare bottom and cyano on the bottom disappears overnight.

 

[Dan_P]

is this always the case? I have a bare bottom and cyano on the bottom disappears overnight.

In the case of the bare bottom, the cyanobacteria are dispersing, moving apart and thinning the mat. If you look carefully you will see this very thin film.