A Fresh Look At Preventing Algae?

jaypeecee

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Hi Everyone!

I have just posted on a cyanobacteria/BGA thread but felt it would possibly be useful to also mention it here as the subject matter is of relevance to algae. That way, there are two separate threads. One dealing with cyanobacteria/BGA (the other one) and this one (the one you are now reading) dealing with the prevention of algae. The link to the other thread/post is here:

https://www.ukaps.org/forum/threads/cyanobacteria-identification-at-last.60496/page-4#post-607135

The essence of this new thread (the one you are now reading) is the importance of getting the optimum ratio of nitrate to phosphate in order to prevent outbreaks of algae. I hope the following will be useful:

https://buddendo.home.xs4all.nl/aquarium/redfield_eng.htm

I hope what I've said above makes sense. In a nutshell, I just thought it would be easier to keep cyanobacteria/BGA and true algae separate - a thread for each.

JPC :)
 
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Interesting! I'm in the process of experimenting with precisely this: the ratio of NO₃ and PO₄ in my fert dosage. I've constructed a table below that summarises the history of the ratios I've been trying.

You can see below that the one time so far that I’ve allowed the ratio to go down to 5:1 I started getting tiny pockets of BGA, by which I mean a few square millimetres that spread really slowly. I think I was on the verge of entering the conditions that make BGA's existence possible.

I have now tried lowering my nitrate again to the same 5:1 ratio, but with lower overall amounts. I will be keen to see if the BGA tries to come back!

Note that I don't have a phosphate test kit, and my test strips only give a fairly crude indication of nitrate (0-20 ppm is its lowest measuring range). So I can't really tell what levels are actually in my water column, but I can accurately say exactly what's in my dosage. So the numbers in the table below relate to my dosage, rather than the content of my water column. However, it seems likely that after a week or two of dosing the water column probably starts approaching the same ratios as the dosage.

My results so far might be providing support for the notion that BGA capitalises on a low ratio of nitrate to phosphate, with 5:1 being close to the boundary condition. A ratio of 7.5:1 caused the BGA to pack its bags and disappear.

I have often seen it said that BGA is "caused by low nitrates" (and I may have said so myself), and I'm sure I've also read that it can be "caused by excess phosphate". My suspicion is that neither statement is truly correct, and that it's the balance of the two that is key.

NO₃ (ppm per week)PO₄ (ppm per week)NO₃ / PO₄ ratioBGA outcome
TNC Complete - triple dose
20​
1.8​
11:1​
No BGA
TNC Complete - "double-triple" dose
40​
3.6​
11:1​
No BGA
DIY salts
15​
3.0​
5:1​
Tiny pockets of BGA
DIY salts
15​
2.0​
7.5:1​
No BGA
DIY salts
10​
2.0​
5:1​
(don't know yet!)
 

jaypeecee

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Hi @Dr Mike Oxgreen

Apologies! The Redfield ratio is actually the N-P ratio, not the NO₃-PO₄ ratio. The table in the Buddendorf article threw me. If you look at the NO₃=10mg/l column and its intersection with the PO₄ = 1.5mg/l row, the number presented is 10. But, the actual ratio of 10 to 1.5 = 6.7. So, we need to add another column to your table above showing the N/P ratio. Sorry about that.

It's unfortunate that you don't have a phosphate test kit. I use the JBL PO4 Sensitive kit. It measures from <0.02 to 1.8 mg/l in nine increments. You can get one for £11.99 and possibly cheaper. I also use the JBL NO3 test kit.

And, finally, a bit more bedtime reading:

https://link.springer.com/article/10.1007/s10021-010-9380-z

JPC
 
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I’m not necessarily chasing the Redfield ratio; I’m just investigating what appears to me to be a link between Cyanobacteria and the NO₃ / PO₄ ratio in my fertiliser mix.

And it doesn’t really matter whether it’s expressed as N / P or as NO₃ / PO₄ in my view. If there is a magic N : P ratio then there will be a corresponding NO₃ : PO₄ ratio.
 

kilnakorr

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Interesting....
I must say I'm not really being this.
Over the years I've had many tanks, with very different setups, and with various amount of knowlegde. I've also experienced a wide varity of algae but not once have I had BGA.
I doubt I've been lucky and hit a magic ratio 20 times, no matter what I changed or added to tank.
 
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Interesting....
I must say I'm not really being this.
Over the years I've had many tanks, with very different setups, and with various amount of knowlegde. I've also experienced a wide varity of algae but not once have I had BGA.
I doubt I've been lucky and hit a magic ratio 20 times, no matter what I changed or added to tank.
I don't believe it's a case of hitting an exact magic ratio; rather I think it's a case of avoiding certain ranges of very nitrate-lean ratios.

I have only experienced tiny amounts of BGA when I changed my ratio by quite a long way, so I suspect the allowable "BGA-free" range of ratios is quite wide. I think it's only when you get down to quite a low nitrate-phosphate ratio that you'd start getting BGA.

I haven't yet experimented with very nitrate-rich ratios (my aim in all of this was to try out some nitrate-lean mixes to make my Rotala wallichii go a bit redder). But I suspect you can go as nitrate-rich as you like and you'll never see BGA.

Therefore my suspicion is that any nitrate-phosphate ratio will preclude BGA, except the very nitrate-lean ratios.
 

jaypeecee

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Hi Folks,

Anyone and everyone can contribute to this experiment. Simply provide the data that @Dr Mike Oxgreen has done. And it would be a big advantage if you own nitrate and phosphate test kits in order to include actual measurements of these water parameters. Then we can calculate the nitrate/phosphate and nitrogen/phosphorus ratios.

JPC
 
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I have ordered the PO₄ test kit you suggested, @jaypeecee . So I should shortly know what my water column PO₄ level is. NO₃ is 20ppm or maybe somewhat less; that’s the best accuracy I have.
 

Geoffrey Rea

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Just my two scents to chuck in the mix, but Cyanobacteria succeeds in anaerobic environments. It’s how it changed the earth’s atmospheric composition by outcompeting anaerobic forms of life. Is there any way you can create an extremely low oxygenated environment and control the N and P ratios whilst maintaining consistency of other nutrients to ascertain the validity of the ratios?

This would mean:

- Outside of a tank for any reasonable levels of consistency
- Fixed lighting intensity/duration/depth or alternatively sealed jars all exposed to the same level of sunlight
- Controlled water at source for dissolved oxygen readings
- Controlled additions of N and P to a fixed volume to ascertain any difference in result between varying ratios

If you have access to Cyanobacteria in your tank, carefully dividing up whatever variant you have between the jars increasing the chance you’re dealing with the same photosynthetic bacteria and having them properly sealed would allow for nitrogen fixing varieties of Cyanobacteria having fixed amounts of nitrogen gas available if you don’t have a controlled and currently identified species.

The most pertinent question I can really ask before going through with the above is has this research already been carried out? Never a point worth overlooking.
 

jaypeecee

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Hi @kilnakorr
You just want NO3 and PO4 test results and maybe presence of BGA?
Yes, that's right. Please also include any (green/red/black) algae that you may have. You could also include the manufacturer's name of the test kits - JBL, API, Sera, Salifert, etc.

Please ensure that the nitrate test kit reports the results as NO3. Some kits, e.g. NT Labs report the results as NO3-N. If so, it's a simple matter of multiplying the test result by 4.43 to get the actual NO3 figure.

JPC
 
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kilnakorr

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@jaypeecee

Ok. Since I do have some algae and changing / upping ferts it might be relevant, but changes take time 🙂
I'm also very unsure about the accuracy of the tests as they do rely on my eyes reading the color right.
Currently my tests shows 15 ppm NO3(Tetra drop test) and 0.4 ppm PO4 (Hanna instruments digital reader, HI 706).
I don't trust the digital reader much, and tests are expensive.😕
 

jaypeecee

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Hi @kilnakorr

Many thanks for your figures...

Currently my tests shows 15 ppm NO3(Tetra drop test)...
Just noticed the digital reader is phosphorous not phosphate. So I have 1.2 ppm PO4.
Hanna instruments digital reader, HI 706
So, the nitrate-phosphate ratio is 12.5. Referring to the table included in the link below, your nitrogen-phosphorus ratio is 20.

https://buddendo.home.xs4all.nl/aquarium/redfield_eng.htm

This puts you right on the border between 'little chance of algae' and 'chance of green algae' but no chance of BGA. This is consistent with your comment that:

I have a little GSA,some staghorn and no BGA.
This is starting to look very interesting.

Please let me know if anyone spots any errors in what I've stated above.

JPC
 

kilnakorr

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This puts you right on the border between 'little chance of algae' and 'chance of green algae' but no chance of BGA. This is consistent with your comment that:
True. But my phosphate levels was much lower until recently.
2 days ago I did a large water change, 60% or so, and dosed to 1.5 ppm phosphate. Been doing twice a week water changes, and forgot to add back ferts, which I believe triggered the GSA and staghorn.
So at the moment I'm upping the ferts, but GSA and phosphate relation isn't a new thing, so not sure my situation is helpful in this experiment. Unless, I get rid of all algae and find myself in the 'magic' ratio;)
 

Siege

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Just my two scents to chuck in the mix, but Cyanobacteria succeeds in anaerobic environments. It’s how it changed the earth’s atmospheric composition by outcompeting anaerobic forms of life. Is there any way you can create an extremely low oxygenated environment and control the N and P ratios whilst maintaining consistency of other nutrients to ascertain the validity of the ratios?

This would mean:

- Outside of a tank for any reasonable levels of consistency
- Fixed lighting intensity/duration/depth or alternatively sealed jars all exposed to the same level of sunlight
- Controlled water at source for dissolved oxygen readings
- Controlled additions of N and P to a fixed volume to ascertain any difference in result between varying ratios

If you have access to Cyanobacteria in your tank, carefully dividing up whatever variant you have between the jars increasing the chance you’re dealing with the same photosynthetic bacteria and having them properly sealed would allow for nitrogen fixing varieties of Cyanobacteria having fixed amounts of nitrogen gas available if you don’t have a controlled and currently identified species.

The most pertinent question I can really ask before going through with the above is has this research already been carried out? Never a point worth overlooking.
Guys, read the above. You can only test it if all tanks are exactly the same. There are soooo many variables.


It is an interesting theory - BUT there is I think a massive flaw in the idea.
Someone who is experimenting adjusting ferts to minimise algae is also probably paying much more attention to their tank than before, manually removing algae and increasing waste removal.

What other changes are they doing? We donot know.

Unless you have the r&d facilities of ADA, Seachem etc, it‘ll be a minefield.

You can tailor make your own ferts but what works on one tank may not work in someone else’s . For example I am increasingly finding my version of heavily planted is very different from other peoples.
 
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