Algae and nitrate

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

 

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

 

Re: Algae and nitrate

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

 

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

 

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