Methods: algae control or growing plants?

[Yo-han]

You mention your pH is 6.4, but you did not mention what the KH was measured at.

What good is that with the other?[/B]

My KH is always between 4.8 and 5.1. According to calculations (tables) that would give me between 45.98 and 51.16 ppm CO2. But that is not how I set my CO2, so that is why I didn't mentioned my KH. I set my CO2 by raising my CO2 (lowering the pH) till my shrimp jumped out. Turned it 0.1 pH back and kept that pH while checking my KH stays stable. This way I have the maximum amount of CO2 my shrimp allow me. It turned out to be at pH 6.4.

I do not rely on a specific ppm for CO2 myself.

I work at it backwards.
I get a system that is stable, then go about looking for possible reasons why.
Then I measure the CO2, and then question how much I can honestly say and know about it.
I do the same for lighting, for nutrients, water column or sediment or both.
Filters etc.[/B]

I didn't set on a specific CO2 amount either, it just turned out to be this as shown before.

I also use 2 DC's as a double check. One with 4 KH and one with 9 KH. If both are the same color green, that would give me about 45 ppm. So my CO2 would be about 45 by both methods. As I said before, I can't test it any more specific.

Still, should not activated carbon and large water changes fix that as well for a control test?? [/B]

WC fits in perfectly if algae would be induced instead of inhibited by a signal chemical. This explains why WC's have a good effect on reducing algae. You take away the chemical, and the algae would no longer be induced.

Also, there's a universally admitted fact: Plant growth will stunt when a given nutrient is deficient.
When plant growth stunts, algae emerges.

Just want to find out why that is. And why does reducing/limiting PO4 lead to a more controllable environment and reducing CO2/NO3 etc. lead to algae. So I suggested sugars, these are used as energy by the plant but without CO2, sugars are not (well) formed because carbon is the backbone of a sugar. Misformed sugars, can be excreted and lead to algae growth. Maybe PO4 is not that important for forming sugars (I believe it's main function is as ATP) and for example magnesium (key atom in chlorofyll) is, so this will lead sooner to algae than PO4 does.

The algae that shows up can sometimes be identified by the nutrient that is missing because is will lead to a certain sugar that favours one kind of algae. For example GSA with very low PO4, and GDA with very low Mg. CO2 because carbon is a keyelement in sugars itself and in plant growth will lead to major problems, so the focus on more CO2 = less algae, fits in perfectly as well!

DISCLAIMER: This is all based on theoretics I didn't checked, but makes sense to me

[Tom Barr]

My shrimp are fine a 80 ppm of CO2. Fish get weird above this, mostly the plecos, in other tanks, I can go even higher due to the higher O2 with the wet/drys.
Discus seem wimpy at 45ppm and beyond.....I do not think they like it. I've had them breed well at 40ppm. Shrimp breed less at progressively higher CO2 levels I've noted.
If you really wanna breed shrimp well, no CO2, no Excel, easy carbo etc. If breeding is less of a concern, then CO2 is fine over a wide range.

In answer to your query, I think plants are VERY well adapted to dealing with PO4 limitations, whereas N and CO2? Much less so.
Hence fast internal recycling of PO4, but this is much more difficult with N, carbon, they need it at every stage, so it's going to cause issues with plant metabolism, PO4, not nearly as much.

In otherwords, plants are much less sensitive to moderate P limitation than N or C.

Regarding the idea about sugars, it could be a dozen other chemical groups that are carbon rich.
It could be a lack of the carbon rich sugars that algae sense also.

Since most all aquatic plants leach about 10%, on average, of their photosynthate that they fix, that also might be a source of chemical signaling.
When that stops, then algae have a good chance to grow.
Let's the algae spores know when someone else is there and growing well. When that stops, they go to town.

A water change might not be enough to start the process.

It also might be secondary, it's not the photosynthate, rather, something the bacteria/some organism in the sediment or on the leaves, that consumes the photosynthate, that then gives off something that prevent algae from growing. When this biofilm, periphyton layer is lost, then the pest algae will colonize.

There's plenty we do not know, and many of these latter hypothesis simply illustrate how little we really know about it.
But there's always some guy posting who claims to know it all about why algae grow. I'm not that guy/gal. Haha

[Yo-han]

Me neither, but wouldn't it be great to know the answer and be that guy!

Sounds like my next study would be biology, with a major in algae/plant growth...

[jonny_ftm]

Should make humans so humble, one of the oldest and simplest photosynthetic organisms in the earth, and we just don't know how they evolve, only some main lines, but no real evidence in details

[Tom Barr]

Well bacteria has laid mankind to waste many times throughout history and continues to do so, algae are a lot more complex than they, I know of only a few species that attack humans, and then there's the red tide and the BGA's that can cause secondary effects via toxins.

[paludarium]

Many studies support the CO2 compensation points for algae are in the 0.1ppm ranges for the higher green freshwater algae species. Here is a review of 16 freshwater species:

Measurement of Carbon Dioxide Compensation Points of Freshwater Algae -- Birmingham and Colman 64 (5): 892 -- PLANT PHYSIOLOGY

Hi Tom,

correct me if I am wrong.
1 microliter ( μL ) per liter = 1 ppm, reference: http://www.engineeringtoolbox.com/ppm-d_1039.html
right?

So, the CO2 compensation points of 16 freshwater algae ranged from 4.8-41.5 microliters per liter (or 4.8-41.5 ppm) at acid pH,
while at alkaline pH they ranged from 0.2 to 7.2 microliters per liter (or 0.2-7.2 ppm).

Obviously algae adapted easily to the alkaline environment. But in the acid environment, I am not sure if algae are doing any better than the aquatic plants? How do we rule out that it is CO2 ALONG that control the algae bloom but not the accompanied acid environment?

Regards,
Erich

[Tom Barr]

Hi Tom,

correct me if I am wrong.
1 microliter ( μL ) per liter = 1 ppm, reference: http://www.engineeringtoolbox.com/ppm-d_1039.html
right?

So, the CO2 compensation points of 16 freshwater algae ranged from 4.8-41.5 microliters per liter (or 4.8-41.5 ppm) at acid pH,
while at alkaline pH they ranged from 0.2 to 7.2 microliters per liter (or 0.2-7.2 ppm).

Obviously algae adapted easily to the alkaline environment. But in the acid environment, I am not sure if algae are doing any better than the aquatic plants? How do we rule out that it is CO2 ALONG that control the algae bloom but not the accompanied acid environment?

Regards,
Erich

you simply use an acid/base system that does not use CO2/HCO3, then see what effects the pH has...........in the acid ranges.......peat,. tannins often do this in natural systems, so that would be one idea.........then other acids and base pairs can be used also.

Then the CO2 can be controlled independently and then deterime if there is much effect on growth, algae, plants etc.......

[paludarium]

you simply use an acid/base system that does not use CO2/HCO3, then see what effects the pH has...........in the acid ranges.......peat,. tannins often do this in natural systems, so that would be one idea.........then other acids and base pairs can be used also.

Then the CO2 can be controlled independently and then deterime if there is much effect on growth, algae, plants etc.......

Thanks Tom.

Aside from algae, according to this study on three aquatic weeds, http://www.plantphysiol.org/content/58/6/761.full.pdf, Hydrilla and Ceratophyllum had CO2 compensation points of 44 and 41 microliters per liter, respectively, whereas the value for Myriophyllum was 19. Most of the algae lay in the range of 15 to 20 microliters per liter. http://www.plantphysiol.org/content/64/5/892.short.

In terms of CO2 compensation points, is Myriophyllum spicatum a more competitive species, but not Hydrilla or Ceratophyllum?

Regards,
Erich

[Tom Barr]

Thanks Tom.

Aside from algae, according to this study on three aquatic weeds, http://www.plantphysiol.org/content/58/6/761.full.pdf, Hydrilla and Ceratophyllum had CO2 compensation points of 44 and 41 microliters per liter, respectively, whereas the value for Myriophyllum was 19. Most of the algae lay in the range of 15 to 20 microliters per liter. http://www.plantphysiol.org/content/64/5/892.short.

In terms of CO2 compensation points, is Myriophyllum spicatum a more competitive species, but not Hydrilla or Ceratophyllum?

Regards,
Erich

Look at Figure 6, this is the most telling figure that all the other info has led up to.

As light starts from say 0-100umol, which weed is photosynthesizing the fastest? Eg, taking up the most CO2?

Hydrilla.

It just kicks the other species' butt when it comes to using up CO2 and growing with much less light.
Eurasian milfoil and coontail both have VERY similar curves, and we find them growing together often in CA.
Both at 0ft elevation and at 7000ft.

Hydrilla, if present, will quickly bury any and all other plants except perhaps floaters like Hyacinth, but even these two will die back and lose due to removal of nutrients in the water column by Hydrilla.

It's an evil weed indeed.

Also, in the CO2 compensation, you need to look at GO activity...........this means that milfoil is poor at photorespiration efficacy, Hydrilla? again, it kicks butt.

Notice that corn, a C4 plant also have a very low GO activity level.........Hydrilla has C4 like metabolism lacking the spatial Kranz anatomy.
That was a later paper from Bowes.