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Fish load

In a recent exchange on Discus and plant tanks: some of the reasons why we
don't/can't add more and more fish to a planted tank. As you add more fish,
the amount of NH4 produce increases. At a certain point, you simply cannot
have enough fast growing plants in the system within that same small space
without excess NH4 building up beyond what the plants can take in.

Then you get algae. Even if the CO2, K+, PO4, traces are all in line.
Having these nutrients in good shape will allow you to pack more into a tank
and also reduce algae presence if you add too many fish so it helps either
way no matter what fish load you have.

I almost universally tell folks with Discus and other higher stocking
planned tanks to use a wet/dry for good reason. These filters rapidly
convert the excess spikes of NH4 into NO3 and NO3 can be removed with a
water change easily on a weekly basis if it tends to accumulate during the
week. Some tanks can handle the high NO3 production but they often get
chronic GW outbreaks(induced by NH4 spikes from fish waste in this case).

NO3 allows N to build up without nearly as much algae threat. Many folks are
accustom to worrying about NH4 as a fish toxin. It's main problem for the
planted aquarium is that of an algae inducer. Very low levels are fine but a
small spike can induce GW, staghorn if higher and then a number of green
attach filamentous green algae. Often, by the time folks get around to
testing the tank, the NH4 spike is long gone but the algae have been induced
and will stop at nothing to finish their life cycle.

I guess if there is a limited nutrient in a plant tank it's NH4, but not
For most planted tanks, it's better plan to add/top off the N needs with
some KNO3.

>>> The conversion of toxic fish wastes  to a less
> harmful substances (AKA "biological filtration") can
> be done without filtering. Healthy aquatic plants
> consume the ammonia (or ammonium)directly, without
> waiting for it to be converted to nitrates.<<

Well the higher the fish load/feedings, the closer you get to having this
bite you. At a certain point this no longer becomes a benefit at all. It
becomes an algae producing problem and there's no way except water changes
to lower it because plant uptake simply cannot keep up with the amount

> In my opinion, discus without filtration is a bad
> idea.  You will end up with bad discus.

Discus from the wrong side of town, a common riff raff street Discus?
It's true though. Yea, it can be done adding a bunch of fish in a small
tank. It's also kind of cruel to some degree. If you put off maintenance and
other responsibilities that come with hobby, you get algae and or dead fish.
It's better to give them a nicer home that's easier on *you* and on the
critters. It'll make everyone happier.
Tom Barr