Dosing silica to encourage diatoms as a form of nutrient control/export
- Thread starter Kairus
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lokii_37
New member
I was thinkng about what you said in regards to diatoms being a "pioneer" species. If the nutrient levels were low enough so that other forms of algea are not able to grow and get a foot hold, could these pioneers be used kind of like a scrubber for the low levels nutrients? Essentailly always pionneering and using up resources before the nasty stuff.
Yes, that's my article. They have my name there as author. You don't see that, Bill? You still using Netscape Navigator? 
Feature Article: Silica In Reef Aquariums
By Randy Holmes-farley, Ph.D.
If the nutrient levels were low enough so that other forms of algea are not able to grow and get a foot hold, could these pioneers be used kind of like a scrubber for the low levels nutrients?
I don't know how useful it is, but every time I dose silicate I shift the green algae on the glass to diatoms, so the premise is seemingly supported with respect to the green algae that grows on glass. I show pics in the article above.
Feature Article: Silica In Reef Aquariums
By Randy Holmes-farley, Ph.D.
If the nutrient levels were low enough so that other forms of algea are not able to grow and get a foot hold, could these pioneers be used kind of like a scrubber for the low levels nutrients?
I don't know how useful it is, but every time I dose silicate I shift the green algae on the glass to diatoms, so the premise is seemingly supported with respect to the green algae that grows on glass. I show pics in the article above.
Yes, that's my article. They have my name there as author. You don't see that, Bill? You still using Netscape Navigator?
Feature Article: Silica In Reef Aquariums
By Randy Holmes-farley, Ph.D.
If the nutrient levels were low enough so that other forms of algea are not able to grow and get a foot hold, could these pioneers be used kind of like a scrubber for the low levels nutrients?
I don't know how useful it is, but every time I dose silicate I shift the green algae on the glass to diatoms, so the premise is seemingly supported with respect to the green algae that grows on glass. I show pics in the article above.
Don't know how they are doing the website, but it seems my script blocker is what blocked out your name on their site.
:lol:
OK, I won't take that personally.
OK, I won't take that personally.
herring_fish
Crazy Designer
I have an RO/DI unit but I personally like some silicate in my tank and sometimes dose it for a mixed NPS plus setup. I use a well designed algae scrubber that takes up a lot of stuff. The only think else that I use is a sock full of carbon that the water runs over.
Why do I need to keep running the RO/DI unit? I know Dr. Adey's advocates using one for ATS users but do I still need it? I'm sure the answer is yes but why?
By the way. If I go slowly, I find it easy to judge how much silicate to use by viewing the result. The tank recovers pretty quickly.
Why do I need to keep running the RO/DI unit? I know Dr. Adey's advocates using one for ATS users but do I still need it? I'm sure the answer is yes but why?
By the way. If I go slowly, I find it easy to judge how much silicate to use by viewing the result. The tank recovers pretty quickly.
RO/DI removes copper and other undesirables from the water that your filtraton will not be especially good at removing.
There may also be substantial ammonia in the water if your water company uses chloramine.
There may also be substantial ammonia in the water if your water company uses chloramine.
herring_fish
Crazy Designer
Won't a powerful ATS take up the copper and ammonia?
hecticreefer
In Memoriam
I do believe that is one of Randy's articlesThough it seems AA has reformatted their presentations making it bit difficult to determine who the author actually is...kind of makes it look like the publisher is the author
Says RHF, PhD right under the title for me.
At least AA pays their authors.
I think you missed this:
They are serving up the author information via some sort of scripting. I had to allow the scripting to run for Randy's name to show up. Though the article was fully readable with the script blocker running.
SantaMonica
Well-known member
Yes algae will consume copper up to a critical point; above that and the copper will kill the algae.
Chloramines can be broken into chlorine+ammonia by the vitaminC / ascorbic acid that the algae produce; the chlorine evaporates, and the ammonia is consumed by the algae. Of course this is all up to a point; beyond this and it probably works in reverse
I wouldn't rely on algae to remove copper sufficiently, but obviously it depends on how much copper is in your tap water and other sources. Some tap water has way, way too much, over 1 ppm. While it was not an ATS, I've had large growths of macroalgae in my system (covering about 10 square feet of surface area) and even with RO/DI, my tank water had more copper than I'd prefer in it.
Chloramines can be broken into chlorine+ammonia by the vitaminC / ascorbic acid that the algae produce
Do you have a measure of how much vitamin C algae release to the water column under normal reef circumstances, and whether that amount can neutralize the chloramine from tap water before it harms things?
Chloramines can be broken into chlorine+ammonia by the vitaminC / ascorbic acid that the algae produce
Do you have a measure of how much vitamin C algae release to the water column under normal reef circumstances, and whether that amount can neutralize the chloramine from tap water before it harms things?
SantaMonica
Well-known member
No don't have any numbers; once I discovered that many FW people dose VC to deal with chloramines, that was as far as I went.
Some anecdotal experience
Some anecdotal experience
Some may find my experience helpful with this.
After reading the above (and much, much more) I decided to try dosing sodium silicate. I bought a bottle from an art store, and started dosing it regularly in my newly resurrected 150 gallon marine tank.
My 'experiment':
1. The tank started out with dry rock only and fine aragonite sand. It was as "sterile" as I could get it.
2. I performed a fishless cycle under complete blackout conditions.
3. Then I started to introduce livestock. Very slowly and deliberately.
4. I forget exactly how/when the diatoms started growing the tank; it's possible they started to 'bloom' before I introduced any livestock. What's important is that they were the first organism to cover the dry rock and the glass after I started to use full lighting on the tank.
Then I started to dose the sodium silicate.
5. Over the next few months, with regular dosing of silicate, the diatoms prospered. They covered all of the dry rock and the walls of the tank in thick brown/gold. The surface of the rock grew slimy with the brown covering. The film on the glass was/is very easy to remove with a magnetic cleaner.
The only other thing that grew in the tank was/is red cyanobacteria. Small areas initially, near a frag I introduced. More importantly, nothing else grew. No green film algae, no hair algae, no coralline algae.
I use my skimmer intermittently (I turn it on once or twice per week), and it would remove nice green smelly slimy skimmate. I would turn it off when the skimmate production decreased (typically in less than one day).
6. About a month ago, I grew tired of the monotonous brown covering on the rocks, and I stopped dosing silicate. Within days, the brown/dark green covering I allowed to grow on the back glass of my tank started to peel off in sheets. I removed some of it as it came off, but largely ignored it. A few bare spots appeared on the rock, but for the most part the rock remained covered in brown slime. The diatom covering the glass grew very slowly, if at all. I now had to clean off the front glass maybe twice a week.
7. At some point coralline algae started to grow. Of note, I had been adding Kalkwasser to top-off water all along. Much later I also started to add Magnesium. This I do recall: the coralline only started to grow after I started adding magnesium. This was maybe two months ago. It started slowly, in small circular spots on the glass, and on the few bare patches on the dry rock that were not covered with diatomaceous slime. It continues its slow growth to this day.
8. Since then, more red cyanobacteria has appeared. Mostly on the sand, but also on the rocks where there is less flow. It does grow over the diatom covering in those areas. Nothing else has grown, as of yet.
9. I started dosing silicate again very recently, in much smaller doses than before, to encourage more diatom growth.
It's way too long a posting at this point, so I will stop and allow others to chime in about what they think may have been happening. I have my own thoughts, obviously. There is also a lot of detail about my system that I left out that may or may not be relevant to the point I'm trying to make, which is this:
controlled diatom growth may be a viable method of nutrient export in marine tanks that make use of a skimmer.
Some anecdotal experience
Some may find my experience helpful with this.
After reading the above (and much, much more) I decided to try dosing sodium silicate. I bought a bottle from an art store, and started dosing it regularly in my newly resurrected 150 gallon marine tank.
My 'experiment':
1. The tank started out with dry rock only and fine aragonite sand. It was as "sterile" as I could get it.
2. I performed a fishless cycle under complete blackout conditions.
3. Then I started to introduce livestock. Very slowly and deliberately.
4. I forget exactly how/when the diatoms started growing the tank; it's possible they started to 'bloom' before I introduced any livestock. What's important is that they were the first organism to cover the dry rock and the glass after I started to use full lighting on the tank.
Then I started to dose the sodium silicate.
5. Over the next few months, with regular dosing of silicate, the diatoms prospered. They covered all of the dry rock and the walls of the tank in thick brown/gold. The surface of the rock grew slimy with the brown covering. The film on the glass was/is very easy to remove with a magnetic cleaner.
The only other thing that grew in the tank was/is red cyanobacteria. Small areas initially, near a frag I introduced. More importantly, nothing else grew. No green film algae, no hair algae, no coralline algae.
I use my skimmer intermittently (I turn it on once or twice per week), and it would remove nice green smelly slimy skimmate. I would turn it off when the skimmate production decreased (typically in less than one day).
6. About a month ago, I grew tired of the monotonous brown covering on the rocks, and I stopped dosing silicate. Within days, the brown/dark green covering I allowed to grow on the back glass of my tank started to peel off in sheets. I removed some of it as it came off, but largely ignored it. A few bare spots appeared on the rock, but for the most part the rock remained covered in brown slime. The diatom covering the glass grew very slowly, if at all. I now had to clean off the front glass maybe twice a week.
7. At some point coralline algae started to grow. Of note, I had been adding Kalkwasser to top-off water all along. Much later I also started to add Magnesium. This I do recall: the coralline only started to grow after I started adding magnesium. This was maybe two months ago. It started slowly, in small circular spots on the glass, and on the few bare patches on the dry rock that were not covered with diatomaceous slime. It continues its slow growth to this day.
8. Since then, more red cyanobacteria has appeared. Mostly on the sand, but also on the rocks where there is less flow. It does grow over the diatom covering in those areas. Nothing else has grown, as of yet.
9. I started dosing silicate again very recently, in much smaller doses than before, to encourage more diatom growth.
It's way too long a posting at this point, so I will stop and allow others to chime in about what they think may have been happening. I have my own thoughts, obviously. There is also a lot of detail about my system that I left out that may or may not be relevant to the point I'm trying to make, which is this:
controlled diatom growth may be a viable method of nutrient export in marine tanks that make use of a skimmer.
Last edited:
I realize that I gave no evidence to support my conclusion. The fact that my nitrates remained less than 10 ppm despite no water changes for >6 months would support that. The thing I was actually trying to achieve was to have diatoms out-compete other algae, which I think it did. The epiphytic cyanobacteria is not of much concern, and it's the only nuisance organism that has survived with the dominant diatom phytoplankton covering the tank.
SantaMonica
Well-known member
A good experiment would also be to add silicates to a tank with a scrubber. Or vise versa.
SantaMonica, why use an algae scrubber and controlled growth and harvesting of diatoms as an experiment? Seems to me that an experiment would be to switch from one to the other and back (over months, keeping everything as stable as possible). This would compare the efficacy of diatoms vs. ATS. Am I missing something?
For me, this is not practical as I would have to build and run a algae scrubber and it's not an option for me.
Nick
For me, this is not practical as I would have to build and run a algae scrubber and it's not an option for me.
Nick
To prove nutrient export, the experiment must show a sufficient amount of exported plant mass to explain a change in nutrient levels. Given that algae contain on a dry mass basis about 5% nitrogen, and contain around 80% water, you would have to be exporting many grams of diatoms to significantly reduce nutrient levels. It is far worse for phosphate. And diatoms have shells which would lessen the percent nitrogen exported. Furthermore, algae exude organic matter, so, there is an additional waste cost for growing them.
So, growing diatoms is not a viable way to remove a significant amount of nitrogen or phosphorous.
Sorry about the confusion. I would say for our purposes diatoms and macro algae are about the same even though diatoms have a shell and the weight percent of nitrogen is possibly lower.
The point I was making was that you are unlikely to grow enough diatoms to make a difference without turning your system into what looks like split pea soup. And then there is the matter of harvesting diatoms.
What would be useful to know is the weight of diatoms per cc we can expect to grow in an aquarium. Then we could calculate some expected nutrient export rates forvyour idea.
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