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Noob question phosphate and phosphorus.

3K views 27 replies 9 participants last post by  BruceF 
#1 ·
Well I was talking to the nice girl at the lfs today and mentioned that my brown algae is not going away she said its most likely is hi phosphates and to use a phosphate mover or neutralizer. I mention im dose NPK and she said to stop or dose less phosphorus.

So phosphates come from the phosphorus I've been adding. Should I stop all together for say a week or two or just cut my dose in half over the same time frame?
 
#6 ·
Phosphorus is an essential element for all life forms. It is a
mineral nutrient. Orthophosphate is the only form of P that
autotrophs can assimilate. Extracellular enzymes hydrolyze
organic forms of P to phosphate. The effect is studied of
different phosphorous concentration on changes in growth
rate of diatom species isolated from Tones River. All
diatoms examined increasing cell division rate with
increasing phosphorous concentration in the medium.
Diatoms, however, were not able to dominate when
phosphate was deficient, although silicate and nitrate were
in excess.

http://www.ijsr.in/upload/228151688Chapter 21.pdf
 
#9 ·
We really do not have enough details to help you based on the information provided.

Light?
Pic of the tank?
Plants? What type, how much, CO2?

Etc...........

Ferts are essential and perhaps the easiest thing in the hobby, but many still have long blamed them for algae and as I often tell folks....."a good myth is very hard to kill".

I dose 10-15 ppm PO4 a week to this tank:



10 ppm to this one:





Algae can be due to many things, but mostly....it's due to folks not addressing the plant needs, which light and CO2 are the dominate issues for 90%(maybe more) of folks having algae issues vs say ferts.
 
#8 ·
As Wolf said, phosphate alone doesn't cause algae and it very well could be a sign of the newness of the tank.

Limiting a vital nutrient for plants is counter productive. Healthy plants can out-compete algae. Also, even if this somehow did work against your diatoms, you'll just get GSA instead.

Grow plants and stop fighting algae.
 
#15 ·
I thought brown diatoms were caused by high silicates. ??

When mine didn't appear be getting any better and in fact seemed to be getting worse even after 3-4 months I finally added PhosZorb to my filter. It made a noticeable difference rather quickly. After several weeks they were gone. I don't know if it was just a coincidence they cleared up when I added the PhosZorb or not, but when they started again after changing my substrate I put the bags back in and they started going away. Again could have been coincidence. But to me it seemed to help. I dose extra Phosphate to put back in what is removed.
 
#16 ·
I thought brown diatoms were caused by high silicates. ??

When mine didn't appear be getting any better and in fact seemed to be getting worse even after 3-4 months I finally added PhosZorb to my filter. It made a noticeable difference rather quickly. After several weeks they were gone. I don't know if it was just a coincidence they cleared up when I added the PhosZorb or not, but when they started again after changing my substrate I put the bags back in and they started going away. Again could have been coincidence. But to me it seemed to help. I dose extra Phosphate to put back in what is removed.

new substrates usually have lots of silicates. there are a few that don't.. keep that in mind as well.
 
#17 ·
I’ve been reading about how carbon is the limiting factor for bacteria. The thesis is that with more carbon available the bacteria will out compete the algae, thereby repressing the algae grow.

I see this all the time that adding more Phosphate I get more algae. I don’t see that as mythological at all. Of course I am not adding any co2 or any excel. Recently I have been increasing the K and not dosing any P and I seem to be getting rid of more algae.
 
#18 ·
I’ve been reading about how carbon is the limiting factor for bacteria. The thesis is that with more carbon available the bacteria will out compete the algae, thereby repressing the algae grow.

I see this all the time that adding more Phosphate I get more algae. I don’t see that as mythological at all. Of course I am not adding any co2 or any excel. Recently I have been increasing the K and not dosing any P and I seem to be getting rid of more algae.
IF plants get the base nutrients they need, they will require more co2/carbon to grow properly.... this will cause algae.
your looking at it backwads. it takes a long time to get past that

i my tank stays at around 5 ppm phosphates and i grow very little algae. i have some in my overflow in areas i can't ever reach and get cleaned occaisionally. it never grows to anything significant.

i get a spot of diatoms here and there in darker places of my tank. or a tuft of black algae on a piece of wood occaisionally. my co2 tank was out for two weeks and i got some black algae then but with the re introduction of co2, some good maintenance i got it under control and is now all gone...
 
#21 ·
This article has few large issues when applying it to the hobbyist tank: temperature is a huge factor and they acknowledge it.

Light is also massive difference.
Flow and replacement water is also very different.

But..what is the real smoking gun here in the research that is different from our aquaria???

Plants!!

You need to find tropical or subtropical temps and then add lots of plants to such systems.

Here's one such article and it shows no correlation between P and N and algae vs submersed plant growth:

http://lakewatch.ifas.ufl.edu/LWTEAMFOLDER/CanfieldPubs/macrophyte.pdf

This addresses the plant absence/presence and temp factors. It also has a very high no# of lake samples!!

you can grow plants without CO2, the question is, at what rate, well, about 10-20X slower and species will compete for CO2 since it is very limiting. If you add a lot of PO4, then the plants will take up the CO2 at MAXIMUM rates since they are not limited as strongly by PO4. This is predicted by Liebig's Law of the Minimum. CO2 Limitations, strong ones anyway, will induce algae since plant growth is very much linked to ample CO2.

A non CO2 tank might have say 3 ppm when the lights 1st come on, then after about 1-2 hours, it'll be almost all gone.

Plants stop growing. a little more CO2 comes in, they get what little is there.
They adapt well to low levels if there's ample time to do so.

This is done at the enzymatic level.

CO2 enriched planted tanks, the plant has much "lazier" and fewer CO2 fixing enzymes. There is ample support in research for this also.

If the non CO2 is limited strong to moderately by PO4, plants still do okay, but they are not growing that fast, but...............they still grow. That is a key point.

If you suddenly remove the PO4 limitation, then what was once a well adapted system enzymatically, now is feast or famine. The plants do poorly in the transition period and you end up with algae.

Bridging ther gap between non CO2 and CO2 is an issue for hobbyists. a good hobby article on this is the Tropica one which the matrix shows how all types of planted tanks still have some growth, even at low light and non CO2 levels, what changes is the rate.

http://www.tropica.com/en/tropica-abc/basic-knowledge/co2-and-light.aspx


I can promise you, I can grow far more species together, in a CO2 enriched system, than anyone might in a non CO2 system.

Non CO2 enrichment has dependency on well, obviously.............CO2, so anything that drives more growth, gets more and more choked by this constraint. One way to think about this is by considering what moderately limiting CO2 is vs strongly limiting CO2 is and their affects on plants and growth.

If you say cut the rates of growth back by 40% via limiting CO2, this is not too bad, the plant can still use many of the same enzymes and does not need to rework the photosynthetic "factory". If you limiting the growth vai CO2 by say 90%, then the factory and enzymes need to be entirely reworked and the system crashes= algae.

Algae grows when plants do not. Since this hobby is based on growing nice planted tanks, I focus there, then algae is not much of an issue.

Examples of PO4 rich non CO2:

you can guess why there's no/little algae in this tank:



But how about this one?
 
#23 ·
I don’t have a problem with limiting growth. The fact that I limit growth by carbon or by light is just my reality. Slower growth is not really a problem. In fact less pruning is not terribly exhausting!

This is from the tropica link.
“In most cases, however, an aquarium plant fertilizer without nitrogen and phosphorus may safely be added to maintain healthy growth. It is often a much more difficult and expensive task to provide adequate light over the plant aquarium.”

So without complicating this thread more the original question was about limiting P. Is it safe to limit P? Sure it is safe. Will it have any detrimental effects? Not many. Will it help with the diatom problem? Most likely.
I don’t see anything in what has been posted that contradicts that statement.

“There were strong positive correlations between planktonic chlorophylls and
total phosphorus and total nitrogen……….”
http://lakewatch.ifas.ufl.edu/LWTEAMFOLDER/CanfieldPubs/macrophyte.pdf

All diatoms examined increasing cell division rate with
increasing phosphorous concentration in the medium.
Diatoms, however, were not able to dominate when
phosphate was deficient, although silicate and nitrate were
in excess.

http://www.ijsr.in/upload/228151688Chapter 21.pdf
 
#24 ·
OP. I dose high amounts of po4 and I have 0.0 algae, if you stop dosing po4 for a week it's not going to kill your tank so feel free to try it. On the flip side I was able to cure GSA by drastically increasing my PO4. I have followed Toms advice for a long while and I have very healthy tanks... You do what ever you think makes since to you, but when you get a minute take a look at Tom's aquariums and the plant growth and health he achives, you will soon agree that he is doing something very right.
 
#25 ·
I don't want to be mean, but for the average person, the articles and quotes may be a bit misleading. Firstly, how many average hobbyists will want to read something speaking of molar weights and attempt to convert them to something they understand? Secondly, your quoting of them seems to imply a causal link that is true and not one that is only true in those particular instances.


“There were strong positive correlations between planktonic chlorophylls and total phosphorus and total nitrogen……….”
http://lakewatch.ifas.ufl.edu/LWTEAMFOLDER/CanfieldPubs/macrophyte.pdf

If I read this article correctly, this one seems to indicate that up until about 15mg/m^3 phosphorus, macrophytes and intermediates are more common than algaes. If my math is correct, this is about 12ppm phosphorus.



All diatoms examined increasing cell division rate with
increasing phosphorous concentration in the medium.
Diatoms, however, were not able to dominate when
phosphate was deficient, although silicate and nitrate were
in excess.

http://www.ijsr.in/upload/228151688Chapter 21.pdf[/QUOTE]


Again, if my math serves me correct, the lowest concentrations of k2hpo4 in this experiment were around 1.74ppm. The higher concentrations (that actually started to lower cell numbers after 8 days) only went up to about 12ppm (interesting concentration when you think about the above study). They report a decrease in population after 8 days with a concentration around 9ppm.

Essentially, this test does not address this persons scenario. First and foremost, what is the OP's concentration of phosphorus in their water? How about substrate (surely algae could use that too)? What if they are already under the lowest test limit? What about above?


If my plants are healthy, I don't fight algae (not that I fight it if it shows up). It really does seem to be as simple as that. Just give your plants some sweet sweet love.
 
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