# gsa and phosphate levels



## jrill (Nov 20, 2013)

Yep, raise it a bit. Try 3 and see what happens.


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## micheljq (Oct 24, 2012)

Hi, there are no known direct relations between algae and nutrients level. What is important is that the plants have what they need. They have more than plentiful of PO4 now. Is there something i miss?

Michel.


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## jrill (Nov 20, 2013)

micheljq said:


> Hi, there are no known direct relations between algae and nutrients level. What is important is that the plants have what they need. They have more than plentiful of PO4 now. Is there something i miss?
> 
> Michel.


I beg to differ. I think the reports of gsa with low phosphate levels has been verified too many times to say that.


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## imcmaster (Jan 30, 2015)

This post is only to explain one cause of GSA in the context of a dosing strategy:

I have been reading about a dosing technique that attempts to give the plants 'what they need and not much more', and that the balance established between N and P (and K to some extent) feeds the plants well and prevents GSA algae.
According to this technique, GSA appears when N present in the tank exceeds the uptake of the plants and P is kept low (near zero). The technique then suggests to slowly raise P (while N is kept constant) until GSA disappears. This is then the proper balance of N and P. 
So I think it is generally known that raising P (for a given N) in some scenarios can prevent GSA. But I also think that applying a rule like this outside of a general strategy may not work. I don't know enough about PPS yet, but expect that the ratios established (between N, P and K) help prevent GSA algae. But as the author of the technique mentioned above says, every tank is different (the different types and amounts of plants will cause the uptake of N to vary from tank to tank) - so the balance of NPK is likely unique for each of us. In summary, you probably have GSA because of an imbalance between N and P, and by adjusting either N (probably down) or P should work.


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## micheljq (Oct 24, 2012)

jrill said:


> I beg to differ. I think the reports of gsa with low phosphate levels has been verified too many times to say that.


The guy says he has 2ppm of PO4 it is not what i would call low phosphates level. I am not convinced, but i am far from being a specialist so my opinion is worth what it is worth. I am just a little surprised by the answer.

Michel.


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## jrill (Nov 20, 2013)

micheljq said:


> The guy says he has 2ppm of PO4 it is not what i would call low phosphates level. I am not convinced, but i am far from being a specialist so my opinion is worth what it is worth. I am just a little surprised by the answer.
> 
> Michel.


Well, his test may indicate 2ppm but we know that hobby testing equipment just approximates especially if we have not taken the time to calibrate our testing solutions. So we test and watch our plants. Since we know that gsa is often a symptom of low phosphate I think that is the obvious place to start. I would still recommend the op raise the level to 3ppm on his testing solutions and go from there.


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## Zorfox (Jun 24, 2012)

I agree to increase PO4 dosing. 

Whether your test kit reads 0 or 20 adding PO4 won't hurt. Your tank is telling you there is an issue. 

Remember, always treat your tank not a test tube.


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## micheljq (Oct 24, 2012)

jrill said:


> Well, his test may indicate 2ppm but we know that hobby testing equipment just approximates especially if we have not taken the time to calibrate our testing solutions. So we test and watch our plants. Since we know that gsa is often a symptom of low phosphate I think that is the obvious place to start. I would still recommend the op raise the level to 3ppm on his testing solutions and go from there.


Thanks, sorry for intruding in the post.


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## Linwood (Jun 19, 2014)

FWIW I had GSA, and started increasing Phosphate over time aiming at about 2ppm as well. The GSA got much better, never went away completely, but definitely improved. So I'll follow with interest to see how yet more affects the OP. 

I should note I also found I needed to increase potassium, as either because of increased plants, or increased growth from the increased phosphate, I started getting potassium deficiencies.


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## jrill (Nov 20, 2013)

micheljq said:


> Thanks, sorry for intruding in the post.


That's why were all here, to talk about this stuff.


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## rick dale (Feb 26, 2014)

*michel*



micheljq said:


> Thanks, sorry for intruding in the post.


No intrusion . I appreciate everyones opinion. And I thank you for your thoughts and opinions. Please , keep them coming. And thanks

Bump: I am going to attempt my first test calobrations tonight in phosphates and nitrates. I will post how things go with the calibrating and tests afterwards. I appreciate the help from everyone. 

I have dry ferts from GLA so I can adjust the mixtures as needed. Once I find out what is needed. Thanks again .


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## rick dale (Feb 26, 2014)

*po4 test calibration results*

Well I calibrated my po4 test kit tonight , and it was off. After calibration , my po4 was 1.0 ppm. Will be doing nitrate tomorrow night.


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## plantbrain (Dec 15, 2003)

imcmaster said:


> This post is only to explain one cause of GSA in the context of a dosing strategy:
> 
> I have been reading about a dosing technique that attempts to give the plants 'what they need and not much more', and that the balance established between N and P (and K to some extent) feeds the plants well and prevents GSA algae.
> According to this technique, GSA appears when N present in the tank exceeds the uptake of the plants and P is kept low (near zero). The technique then suggests to slowly raise P (while N is kept constant) until GSA disappears. This is then the proper balance of N and P.
> So I think it is generally known that raising P (for a given N) in some scenarios can prevent GSA. But I also think that applying a rule like this outside of a general strategy may not work. I don't know enough about PPS yet, but expect that the ratios established (between N, P and K) help prevent GSA algae. But as the author of the technique mentioned above says, every tank is different (the different types and amounts of plants will cause the uptake of N to vary from tank to tank) - so the balance of NPK is likely unique for each of us. In summary, you probably have GSA because of an imbalance between N and P, and by adjusting either N (probably down) or P should work.


Funny, I do not get GSA and I have dosed 5ppm of PO4 2x a week, NO3 at 30-45 ppm a week. 

Go figure.
And after 20 years or so on many different tanks, different tap waters.......different places I've lived, the same results. 

Saying stuff like "every tank is different" is non informative. 
Maybe it's more to do with each aquarist is different. 

Rather than the method..........after all every method has plenty of examples of failures. 

There are many larger factors with planted tanks than mere ferts, which are one of the EASIEST things to rule out. People waste a lot of time fiddling with ferts.

Me? I prefer to garden and scape. 



Bump:


Linwood said:


> FWIW I had GSA, and started increasing Phosphate over time aiming at about 2ppm as well. The GSA got much better, never went away completely, but definitely improved. So I'll follow with interest to see how yet more affects the OP.
> 
> I should note I also found I needed to increase potassium, as either because of increased plants, or increased growth from the increased phosphate, I started getting potassium deficiencies.


PO4 is fairly easy to rule out, CO2 is the other factor. 
So if you do it step wise, you should be able to dial the CO2 in really well and have to only clean the glass maybe once a month or 2, or three etc.......I only clean my 70 Gallon Buce tank maybe once every 3-4 months.


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## rick dale (Feb 26, 2014)

*co2*

Any tips on dialing in the co2 correctly ?


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## Raymond S. (Dec 29, 2012)

Don't remember which person it was that responded to my thread earlier when
I asked a question about dosing levels, but they said that...A...KH2POP4 is about
the only nutrient that we normally dose which CAN be over done/w harmful 
side effects with relatively low amounts of an over dose.
Simply meaning that the other normal to dose nutrients need much more of an 
over dose to be harmful.
And that...B...the 1/64th tsp of it is actually over the amount needed for the EI 
dosing level to be reached in a 10g tank and therefor it would be more accurate 
to use a liquid solution on this nitrients as 1/80th tsp is closer to accurate and
this is obviously not possible in measuring spoons.
I use 8.5g on the calculator to allow for sub etc and it recommends 59mg of the
KH2PO4 to get "your target" of 1.30ppm of PO4 when the calculator is set on EI.
Side issue so to speak: I have some Rotala Magenta that have yet to respond to any changes I've
made in the ferts. They have very erratic/poor growth. The KH2PO4 is about the only nutrient
that I have not changed.
I then used "the results of my dosing" to find the 1/64th tsp level and it's 1.90
in ppm.
So what is the "right amount" if the calculator says that for EI which I presume to
be high enough to be in excess so as not to short anything of nutrients...is 1.30ppm
yet here you suggest 3.00ppm.
First, I'd like someone who knows to actually state it that this info I have is not true about it being harmful in just small quantities over the recommended amounts.
This is my actual main concern in this matter.
Second, I'd like to know an estimate of just how much it may negatively effect
the plant growth if a person stayed/w the recommended amount as it pertains to the plants being short some of what they need to balance the "N" in the dosing...
Obviously shorting any nutrients can hinder plant growth once it becomes low
enough. I'm just wondering why the calculator uses 1.30ppm as "the target" when
this thread suggest more is necessary.
Please don't take this as any challenge to what has already been stated by our
much more learned members than I.
This is to clarify things in my mind on this subject as it may also be a subject of
interest to "others" on the matter especially where the "overdose" issue is.
KH2PO4 is often recommended as a solution for GSA but usually they don't get
very specific on the amount as this thread has and I therefore decided to bring 
this up now.


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## mattinmd (Aug 16, 2014)

I've heard the same about phosphate doses being dangerous, but as best I cant tell the lethal dose of K2HPO4 to fish is really quite high.

This MSDS:
http://www.vaniperen.com/getattachment/99a623d7-c009-4afc-8d12-0dce16cec11a/Monopotassium-Phosphate-Horticultural-Grade/MSDS-Monopotassium-phosphate-Iperen-Int-ENG-3-0.pdf.aspx?dcmslastmod=20140704131841343

Suggests that the LC50 for fish of K2HPO4 is 900mg/L, which is 490ppm of PO4...

They also have an EC50 for "other organisms" at 2ppm, but there's no specification as to what that effect is... They used Potamogeton, a plant, so I can only assume the effect is increased growth...

Now, admittedly that MSDS has an interest in downplaying the toxicity to fish, but it is also the only place I've found a specfic concentration... other places I find things like "phosphates are not toxic to fish except at very high concentrations" and "concentrations above 1ppm can cause algal blooms, depleting oxygen and suffocating fish".

Based on those I'd suggest that KH2PO4 is quite safe, unless you manage to end up feeding a massive algae bloom and don't have sufficient aeration of your tank.

I'd love to see numbers to the contrary, as I've often wondered where the "danger line" is...


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## rick dale (Feb 26, 2014)

mattinmd said:


> I've heard the same about phosphate doses being dangerous, but as best I cant tell the lethal dose of K2HPO4 to fish is really quite high.
> 
> This MSDS:
> http://www.vaniperen.com/getattachm...NG-3-0.pdf.aspx?dcmslastmod=20140704131841343
> ...


Why would MSDS have an interest in downplaying the toxicity to fish ?


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## Diana (Jan 14, 2010)

Increase the rate SLOWLY and monitor the fish. 
Maybe increase it by 1 bps then wait 24 hours, watching the fish. 

If the fish which normally swim mid-tank or lower are at the surface, this is too much. If they are gulping air this is way too much. We are not talking about a surface dwelling fish- it is normal for hatchets and gouramis to be there and for Anabantoids and Cories to take bites of air.

If the fish are hanging out at the surface, then dial the CO2 back, perhaps .5 to 1 bps less. If they are gulping do a water change and dial it back perhaps 2 bps less. (Large tank as discussed above, where the CO2 might be 5-8 bps)

Another way to tell is if the difference between CO2 on and CO2 off, tested at the same time of day creates a shift in the pH of 1 unit, then that is just about 30 ppm, and is usually just about right. 
So, test the pH before the lights come on. Lets say it is 7.5. 
Then turn on the CO2 and give it at least half an hour to circulate (lights still off). If the pH tests 6.5, then you have something pretty close to 30 ppm of CO2


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## mattinmd (Aug 16, 2014)

rick dale said:


> Why would MSDS have an interest in downplaying the toxicity to fish ?


Why would an airline have an interest in downplaying the risks of a plane crashing?

I'm not saying the company is going to outright lie or falsify data. However, chemical companies do have an interest in conservatively stating the risks associated with their products. 

If one well controlled study says 300ppm is dangerous, and 100ppm is safe, and another less well controlled study says 200ppm is dangerous... the MSDS is going to say 300ppm, unless a regulatory body is convinced otherwise and forces them to change it.

That MSDS is not designed for use by aquarists in determining what is safe, it is designed for use by the chemical companies customers to determine if they need to perform costly cleanups after a spill ends up in a lake. Your customers generally don't appreciate it when they find out you over-stated the risks and they wasted 5 million dollars last year on a cleanup that wasn't really necessary...


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## LFM (Sep 18, 2014)

Am I missing something about phosphates? I'm under the impression that phosphates are a nuissance "nutrient" and should be irradicated from your water because of the adverse effects they have in terms of algae proliferation. 

Reasons for me thinking this:

1.
The phosphate test kit pamphlet suggests that the closer to zero the better and says that excess algae in your tank could be contributed to high phosphate levels.

2.
They promote algae growth

3.
At least with the plant supplements I use (Seachem trio flourish, excel, iron) there are no phosphates in them which would infer that phosphates are not needed for your plants

4.
Most importantly, my phosphate levels are below 0.25 and all the plants in my heavily planted tank look so great that they actually look fake and I have absolutely no algae problems.

Something isn't adding up here.

:confused1:


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## mattinmd (Aug 16, 2014)

LFM said:


> Am I missing something about phosphates? I'm under the impression that phosphates are a nuissance "nutrient" and should be irradicated from your water because of the adverse effects they have in terms of algae proliferation.


Sounds like you are taking advice from reef and non-planted tank folks... If you have no life forms that need phosphate, then yes, it is a nuissiance.


However, phosphate is not a nuisance nutrient in a planted tank. It is conclusively proven that phosphorous is an essential macronutrient for plants. They will die in its complete absence. Plants need by more phosphorus than they need iron, by quite a large margin... That's readily proven scientific fact.

Try looking at the dry analysis of some plants, notice that phosphorus is in %, while iron is in ppm.
http://www.extension.umn.edu/agriculture/nutrient-management/docs/AG-FS-3176-1.pdf


However, you are already adding some phosphorus to your tank on a regular basis, it is present in reasonable quantities in fish food, as is nitrogen. This source is often enough for low-tech tanks, and would appear to be enough in yours since your phosphate isn't zeroing out.


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## micheljq (Oct 24, 2012)

Phosphate is not a nuisance nutrient at all. I once had high levels, let's say 5ppm and more for months and no algae problems were observed in my tank. It's and old myth.

On the contrary i had my worst algae issues when PO4 levels were low, near zero, when the plants were starving for nutrients.

Michel.


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## Linwood (Jun 19, 2014)

plantbrain said:


> PO4 is fairly easy to rule out, CO2 is the other factor.
> So if you do it step wise, you should be able to dial the CO2 in really well and have to only clean the glass maybe once a month or 2, or three etc.......I only clean my 70 Gallon Buce tank maybe once every 3-4 months.


THanks, but low tech (well, I do use Excel, but not sure if that operates the same way). 

How often one cleans the glass is also pretty subjective; I have a neighbor that does it about every 2 years, but his guage is whether he can tell if the light is on in the tank (ok, that's my interpretation -- you certainly can't see the fish). 

:hihi:

But with the added phosphate, I'd say I'm down to every 1-2 months. The bigger issue is on one specific plant (an Anubias), that is not all that slow growing actually in this case, some of the leaves are being just covered, yet the rest of the tank remains fairly clear. 

The one thing I can say for sure is that the GSA went way down for me when I started added additional phosphate (not just what was in comprehensive, equilibrium, etc.).


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## LFM (Sep 18, 2014)

Interesting.
Is there a general phosphate level one would recommend keeping?

I know in another thread I said I'd consider taking out my phosguard but I haven't yet because I operate under a very simple principle: Don't fix anything that isn't broken.


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## mattinmd (Aug 16, 2014)

I aim for around 1-2ppm, which is consistent with EI low-light (which calls for 1ppm dosed once a week).

EI aims for somewhat higher than that, dosing 1.3ppm 2-4 times a week. 

If there is no plant uptake, the upper limit of what EI can cause is 10.4ppm (assuming 4 doses a week and 1 50% water change weekly 1.3ppm *4 doses *2 water changes to eliminate). Actual levels in EI will be your weekly dose minus whatever the plants end up using in a week, times 2.

pps-pro goes 0.1ppm/day, or 0.7ppm per week, slightly under EI low-light, but also based on smaller or no water changes.


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## FatherLandDescendant (Jul 24, 2014)

mattinmd said:


> EI aims for somewhat higher than that, dosing 1.3ppm 2-4 times a week.
> 
> If there is no plant uptake, the upper limit of what EI can cause is 10.4ppm (assuming 4 doses a week and 1 50% water change weekly 1.3ppm *4 doses


I thought EI was dosed 3x a week:confused1:


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## Linwood (Jun 19, 2014)

LFM said:


> Interesting.
> Is there a general phosphate level one would recommend keeping?


I've always heard about 1/10th the amount of nitrates.

But with the different ways people report nitrates (and maybe phosphates) I do not know for sure if that's 10th the PPM measurement from (say) the API kit.


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## mattinmd (Aug 16, 2014)

FatherLandDescendant said:


> I thought EI was dosed 3x a week:confused1:


That's common, but a wider range is allowed. Tom Barr's 2005 paper on it calls for 3-4x a week for macros and 3x/week for micros.


http://www.barrreport.com/forum/bar...tive-index-of-dosing-or-no-need-for-test-kits

As a side note, back to an earlier topic, Tom's paper suggests:



> PO4 at very high levels can influence alkalinity (KH) above 5ppm-10ppm.


Which suggests at least one tank problem with elevated PO4 levels that are much lower than the 400-some-odd ppm that is the LC50...


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## LFM (Sep 18, 2014)

Is there a difference between the phosphates that is in your tank water and dosing with phophorous?
For example:
would phosguard also absorb phosphorous as well phosphates thus dosing phosphorous with phosguard in your filter would be like throwing your money away?
do plants just need the phosphorous or phosphates?
does the phosphorous that you add in your tank turn to phosphate and then your plants absorb the phosphorous?

Bump: Nevermind...I just checked out a phosphorus nutrient supplement and its in a form of phosphate. Disregard.


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## mattinmd (Aug 16, 2014)

Heh, yeah, I'd suggest not trying to add straight phosphorus to your tank... 

But seriously, pretty much the only sources of phosphorus as a fertilizer are various forms of phosphate.. phosphoric acid, monopotassium phosphate, di/mono ammonium phosphate (not recommended for tanks), orthoposphates, polyphosphates, etc...


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