Algae and nitrate

[paludarium]

I am thinking about what Diana Walstad has mentioned, algae doesn't take up nitrates if the ammonium concentration is more than about 0.02 mg/l. That means, algae DO uptake nitrate under some certain circumstances, for example when ammonium in under 0.02 mg/l, right? Is there any other possibility that will also force algae to absorb nitrate, pH? light intensity?

 

[Tom Barr]

Re: Algae and nitrate

No, algae have no problem taking up less than 20ppb of NH4 depending on the species in question, they will also use organic N as well as NO3.

You will kill your plants long long before you will hurt/limit algae.

If the total N is less than 20 ppb, that is extremely rare and rather tough to measure also.

Organic N can supply a fair amount of N to the algae also, Organic N is decomposed into NH4 at a slow rate. Harder to measure if you only sample from the water column as it is typically used up as it is produced.

Regards,
Tom Barr

 

[paludarium]

Re: Algae and nitrate

I am confused, you mean that algae also absorb nitrate irrespective of the environments. But you also wrote that the production rate of NH4+ is what generally will cause an algae bloom, not the NO3- and PO4-3 so much in established tanks. How comes there won't be algae blooming when we add nitrate into the aquarium? merely because of a better plants growth?

Thank you.

 

[Tom Barr]

Re: Algae and nitrate

No,

Inducement(think germinaton in seeds) of algal spores is quite another matter versus simply getting the requirements for growth from Nitrogen.

Once the algae spore is induced by NH4 at a high enough concentration, then it will use both NH4 and NO3.

NO3 does not induce algae though, but once "adult" algae is present, it will use NO3 as well.

DW makes no mention of inducement nor seems to know that NH4 induces algae in planted tanks at higher levels. Many assumed NO3 caused algae blooms. But you/we can add lots of NO3=> no algae bloom, add a small amount NH4=> algae bloom.

Same reason why plants cannot have all their nitrogen from fish waste in a higher light CO2 tank=> it all starts out as NH4, not NO3.


Regards,
Tom Barr

 

[paludarium]

Re: Algae and nitrate

Thanks for the reply. Since the "adult" algae also use NO3 once they exist in the aquarium, do we have to treat/kill adult algae first before dosing the water column with normal amount of NO3, or should we even stop dosing?

 

[Tom Barr]

Re: Algae and nitrate

Thanks for the reply. Since the "adult" algae also use NO3 once they exist in the aquarium, do we have to treat/kill adult algae first before dosing the water column with normal amount of NO3, or should we even stop dosing?

Adult algae do not live long.......so if you maintain good conditions, attack the adults and trim/remove them, then they do not come back.

If you keep varying the CO2(confuses the plants), do something to mess up the NH4 uptake of the plants, then you will keep breeding new algae.

I just trim off algae etc, some folks add Excel(works better IMO than H2O2 etc, but both work if you do not get too crazy, I still prefer trimming and manual removal).

Some claim they find it easier etc to use Excel or H2O2, I personally don't if you re set the tank and clean the tank good.

Only a bad case of BGA and GW are the only algae secies that seem to need more than this method to control(they get a 3 day blackout or UV/Diatom etc).


I do not change the KNO3 dosing when algae is there, but I most certainly get rid of the algae first, then reset the tank, does not matter if the NO3 or PO4, Traces etc is dosed, it's still in huge excess relative to the algae if you have plants in there.

Oh, BTW
One bad thing about Diana's reference to this point you made on NH4/NO3 uptake in algae: it's for a marine phytoplankton, not all FW algae, and something not too common in aquariums :gw

A good specific reference helps, other wise you are comparing apples and oranges. She did a similar thing with Fe limitation(Marine phytoplankton) as well as PO4 in Lake Tahoe(Tahoe wetlands are N limited actually, but the open water is PO4/Fe and nearly everything else limited, which is why is it clear, at least sort of for now, but it will not be for much longer).

Regards,
Tom Barr

 

[paludarium]

Re: Algae and nitrate

Thanks, Tom. What if we add some Nitrosomonas, Nitrococcus and Nitrobacteria into the aquarium after pruning and WC, do they help to prevent NH4 from inducing algae bloom? LFSs sell these bacteria here in Taiwan, and many folks BELIEVE that adding these bacteria will achieve a better plants growth and healthy fish, although I never had a try.

 

[Tom Barr]

Re: Algae and nitrate

Well, for any of these bacteria to work, they need a lot of O2 to do so and they need to be a stable place to grow and they need to be actively growing, otherwise it takes awhile and by then, all the plants have removed it and the algae are inticed to grow.

Don't bother with that stuff.

Regards,
Tom Barr

 

[paludarium]

Re: Algae and nitrate

Thanks. I've found an interesting article from Arnold J. Bloom. http://www.plantphys.com/printer.php?ch=12&id=158 According to his finding from terrestrial plants (like wheat), I don't know if I could apply it to the aquatic plants or algae, "elevated CO2 inhibits NO3– photoassimilation. Therefore, when wheat plants receive NO3– rather than NH4+ as a nitrogen source, the CO2 enhancement of shoot growth halved and CO2 inhibition of shoot protein doubled. This will likely have major implications for the ability of plants to use NO3– as a nitrogen source under elevated CO2. "

I remenber that you told folks to crank CO2, and high CO2 concentrations would probably inhibit algae bloom. Actually it works for me. As I have read the above mentioned article, I wonder if high CO2 concentrations in the aquarium also inhibits adult algae from uptaking NO3, and thus algae will be controlled. Am I right?

 

[Tom Barr]

Re: Algae and nitrate

It would be nice if that were the case, but no, algae also like CO32 as much as plants, they just need much less of it.

I did an algal test with attached periphyton under high and ambient CO2 and O2 in various combos.

Algae grew the same for the most part in all treatments.

One treatment I did not try, low CO2 and low O2(below ambient conditions).

I will talk more about that later.

But FYI, wheat grows better with NO3 than NH4, which is counter to what is generally taught, so do many diatoms.

Regards,
Tom Barr