N:P:K

[Karin]

N and P. Are these forbidden to fertilize the water column in an Apisto planted tank? Which are the best strategies to do it?

 

[dw1305]

Hi all,

N and P. Are these forbidden to fertilize the water column in an Apisto planted tank? Which are the best strategies to do it?

No, you can add fertilizers. Nitrate (NO3) isn't toxic to fish (even at quite elevated levels) when it is added a salt (from KNO3) rather than being the "smoking gun" of previously elevated levels of NO- and NH3/NH4+.

I use a technique I've called the "Duckweed Index". Basically you use the health of a floating plant to tell you when you need to add fertilizer. I chose a floating plant to take CO2 out of the equation.

The aim is to maintain low levels of plant growth.

Details here <"Duckweed Index"> (towards bottom of the thread).

cheers Darrel

 

[Karin]

Thanks Darrell. It is exactly what I needed to know. My duckweed and Pistias are showing some kind of deficiency. Probably N. They are a little yellowish, pale growing, but I am adding regularly very little K+, Ca2+, Mg2+ and micros. I was afraid of using it as KNO3 in my apisto tank although I do it in my planted tank as Apistos are said to be sensitive (I suppose they are then sensitive primarily to NH3/NH4+ and NO2-.


Thanks for your answer and the link! My plants are grateful!

 

[dw1305]

Hi all,

My duckweed and Pistias are showing some kind of deficiency. Probably N. They are a little yellowish, pale growing, but I am adding regularly very little K+, Ca2+, Mg2+ and micros. I was afraid of using it as KNO3 in my apisto tank although I do it in my planted tank

That sounds like a nitrogen deficiency.

If you ignore carbon (C), plants need about x10 more nitrogen (N) and potassium (K) than the other elements (including phosphorus (P)).

as Apistos are said to be sensitive (I suppose they are then sensitive primarily to NH3/NH4+ and NO2-).

Yes, you want to remove the NH3/NH4+ and NO2- as rapidly as possible. I like high levels of oxygenation and plenty of plants. If you can ensure that the oxygen supply always exceeds the Biochemical Oxygen Demand (BOD) then you have nitrification covered.

A lot of the concern about NO3 mainly applies to non-planted tanks, where water quality will nearly always be worse than in planted tanks. People go to great lengths to lower nitrate levels (using out-gassing as N2 in a plenum, ion exchange resins, huge water changes with RO etc.), but all they really need to do is use plants as "nitrate sponges".

cheers Darrel

 

[Karin]

Hi all!

Thanks Darrel, perfect... lots of plants are the best to keep nitrates at low levels and being useful. My tanks are usualy a tangle so I' ll add a little KNO3 without fear at the apisto tank then, looking for improvement in floating plants first and in plants in general. Yellowing probably will improve.