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Re: PO4/NO3

I regards to adding more fish:

> ok, ok. This is well known. But if I haven't added any fish so far is
> because  fishes won't give only NH4+ to the tank, but many other things ...
> organic compounds of any kind that, sooner or later, will become not only N
> source but P source and traces source as well.

The main source of fish waste as it effects plants and algae is Nitrogen,
not "other things".

 We are adding CO2. We have good light. You also have carbon(which will take
care of the problem nutrients/organics in the start up phase and removes
ammonia). Plants will use up P/N fast as you've seen. You'd  have to add a
fair amount of fish load to have this (other stuff P and traces) to become a
problem at this point.  There's been work done analyzing fish food and fish
waste for it's content. If I can add 1.5ppm  of PO4 and do not get algae and
also add a lot of traces also, is it the PO4/Traces or the NH4/NO3? Or
unknown organic?

 Water changes will take out a large volume of the organic(or carbon).
Plants and algae produce most of the organic(DON) in the system anyway, not
the fish. Herbivores/fish produce NH4/Urea mainly as it related to
production. Filters will reduce that portion(Nitrogen) down leaving PO4 to
build up in tanks that get no water changes(no export except removal of
biomass-plants /algae/chemical removal or water changes).

> That sounds to me only 1
> thing: dynamics becomes more difficult to understand!

Well, not really. If you have a moderate amount of fish, things are quite
fine and better actually than a tank with no fish/herbivores/critters. This
is the balance part. You under shoot your maximum sustainable fish load on
purpose and add the needed nutrients via the inorganic fertilizers to make
up the difference for the plants. You do not want to over do the fish load
or get close to that level. If you screw up or over feed and your at the max
level things are very close to becoming unstable and giving you an algae
bloom. There is a happy mid range of fish/addition of inorganic nutrients.
We need a safety net.

 NH4/Urea is perhaps the major reason why we cannot have more fish in a
plant tank, same could be said for any fish tank. Normal fish only tanks
don't have high light, trace elements so algae is not a pesky problem. Water
changes can work but the system becomes more unstable at certain point.
There is a fish load that will stabilize these tanks just like ours.
 
>> Well the substrate get saturated at some point if you have iron in there.
> 
> I assume there is no iron in the substrate for what I know. So I don't know
> where PO4 goes when it precipitates.

Well having no iron means _less_ will be bound (PO4) in the substrate. So
the assumption that the uptake is going to the plants/algae is even _more_
valid in that case.
 
>> Filter usage, fish uptake etc can be assumed to be negligible. So all your
>> left with is plant and algae uptake. No algae then-> all plant uptake.
> 
> Algae are there, as you see from the pics.

Nice growth of algae and plant. Have you gone in and cleaned the tank?
Removed all of it that you can? Then keep up on the nutrients? You can clean
that up but it takes some elbow grease, nutrient management alone will not
get rid of the problem. Just clean well, remove/vac up detritus/clean
filters/do water changes regularly/ scrape off algae on
glass/walls/rocks/equipment, dose nutrients well right after a big water
change. Repeat. Add algae herbivores, keep up on nutrients. It will take
some work to realign the tank but thereafter it's smooth sailing as long as
you don't forget to dose your tank/feed the fish etc. This takes about 2-3
weeks to correct most any problem if you have the right levels of nutrients
and do the water change maintenance routine.
 
>> NO3/CO2 are the biggest issues for most folks though. Nothing goes right if
>> you louse those up.
> 
> i'll measure CO2 directly, not deriving from KH/pH relation.

Well, you double check the pH throughout the day. Check once in the morning,
once in the evening. Do this for a few days to make sure there's not just an
aberration. You can try to see what the CO2 is from a direct reading but IME
they are not as close as the table nor as consistent. The table has not
failed folks and is a good reference for CO2 determination. I'd stick with
that personally but just make sure before moving on. Overlooking that the
CO2 is a very common mistake that even the best folks get nailed on. I
learned that part through a lot of experience. It's the only way to get at
the root of many problems in planted tanks.
 
Adding PO4:
 
> so kinda of two pulses of 0.5ppm each.

Sounds fine. Wait till it drops to 0.0ppm. Count how long. Think back to the
assumption made in the first part regarding uptake of PO4. Can you now
assume that the the drop is due to plants (assuming you have removed the
algae)? Remove the algae manually. All that will left is the plants for
uptake. You will still see the same drop. Algae just don't pull that much
PO4 out nor need that much to get real ugly in your tank. The idea of
staving your plants to beat the algae to get good plant growth is not well
founded.

>> Careful since if you add too much NH4 you will get algae. Or dead fish if it
>> gets too high.

> 0.24ppm is too high? the problem is that AC will remove it very fast,
> preventing plants to uptake it!

I think .05ppm to .1ppm would be enough. Don't worry about the filter. Just
watch for algae and plant responses. It would be difficult to assess how
much the filter is "eating". Also consider all the surfaces on each gravel
grain as part of the bacterial colony.

> anyway today I added 0,24 ppm NH4 too. After only 1 hour I read 0.05ppm. It
> really goes away fast. Difficult to say where it goes: activated carbon
> and/or plants?

Likely both to some degree. How much? Again very hard to say. So take the
carbon since that is easy. Now you better assess where the NH4 is going.
Carbon says right on the packages "will remove ammonia".
Bacteria/algae/plants will use it up. Removing the algae manually(or by a
herbivore) will take them out of the picture so then it's algae and bacteria
only now. Now things are far simpler and easier to think about.

If you had more fish .......you'd get more NH4 being produced at nice low
levels and supplemented with KNO3 would give a nice balance of Nitrogen
species. It's fine if the bacteria get the NH4 also. As long as the plants
get a little of it (NH4). I know a way to test to see how much (ratio) NO3
and NH4 is being used by bacteria vs the plants and also all
three(algae/plants/bacteria). All I need is grant money:).

But the short of all of this is that planted tanks will do very well with a
moderate amount of fish vs no fish or too many fish. This thread is a
plausible reason as to why.


> how much 0.24ppm NH4 is compared to NO3? if it goes aways so
> fat should I add NO3 anyway (maybe in a lower dosage)?

You could run your tank at lower NO3 levels and be okay. But remember, since
the NH4 is quickly converted and it's being added rightfully(frightfully) at
low levels you don't have a long time in between dosing times unlike NO3
which can supply a decent amount of Nitrogen to the plants for several days
at a time.
 
I had higher fish loads and try this balance to see how well it would handle
things. It playing with fire unless you have a big filter(in case of NH4
spikes, and that will happen at some point to the tank no matter how good
your testing is and dosing).

On the other extreme you could run the tank too low on NO3 and or NH4 and
stunt your plants. I played with this idea and found a large number of
plants had different N limited tolerances. I tried to supply mainly NH4
instead of NO3. The best road seems to be the fish(some of which should be
algae eaters) for the NH4 and the aquarist for the NO3.

I personally shoot for 5ppm of NO3 using KNO3 if I have fish or a higher
fish load. With very low fish loads, I shoot for 10ppm using the inorganic
KNO3. I figure that the added fish waste will make for the difference.
My practical experience seems to indicate this to be true and manageable.
Your management may vary.

Regards, 
Tom Barr