You made it, you did it, you got the plague!
Something tells me you finally got more light, you're thinking about
CO2, you are fertilizing, your tank is full of plants, and now all of a
sudden BOOM there is algae. Green water, green spots, green hairs short
and long. It's everywhere, growing at alarming rates, covering the plants
you set out to nurture and adore, it is stifling! Well, sorry if I do not
sound surprised, but this happens all the time, and yes, even the best of
us have it or had it. Not to worry there are approaches you can take to
remove this infestation. First lets dispel a few myths, or at least list
These are all the answers, or are they. These are the excuses I have
heard again and again. Are there any truths in these "Words of
- Algae killers take care of it.
- Liquid Fertilizers cause it.
- Terrestrial Fertilizers cause it.
- Bleach everything.
- Heating cables in the substrate will get ride of it
- Wrong gravel, UGF, Power filters, lack of or presence of CO2,
- Salt will help.
- Laterite will make it appear.
- Lights are to blame.
- More water changes, yea that's it.
- Phosphate absorbers, naa.
- The Iron in my tap water combined with what's in the
Let me start with one assertion, the driving force in all algae control
measures, the one truth that most of the advice stems from.
Algae control is all Nutrient
That's it. Pretty simple, right? All you have to do is
maintain the correct "Balance" and everything is great. Well
this is at least the challenge. It is all about details. Like anything
else in the hobby, details, the little things, that's the key. We can talk
of individual factors that may be attributed to the presence of algae, and
your local conditions may favor one imbalance that makes your solution a
little different than say, mine. None the less, in the end it still was an
imbalance that was the cause of the problem, and rectifying that, solved
the algae bloom.
Now you are here because you have algae and want to rid your tank of
this annoying presence. Weather you're running a fully planted tank or a
fish only tank the same rules apply. However I am going to gear my
discussion towards the plant tank people. The fish only people can always
just turn off the lights for a few days. The Aquatic gardeners however are
not as fortunate and their task is a little more detailed, but not very
hard. This page will also take the approach that you are involved in the
maintenance of the tank. I am not one for setting up general rules to
blindly follow and therefore I prefer to start from scratch. But that is
Let me start with a link. There is a paper written by Paul L. Sears and
Kevin C. Conlin, their take on this issue is the one I follow. They
performed a case study on the effects of different nutrients on algae
growth rates. Their conclusions are sound and are what I base my approach
on to this day. For those of you who would like to read their work and
make your own decisions their case
study is available online.
Algae is a plant and you just created an environment perfect for plants.
So, it makes sense then, that the algae is doing well in the environment
you have carefully created. Aquatic Plants require 4 basics to grow:
light, nitrogen, phosphate, and potassium. You've stuffed all kinds of
light up in that hood, your fish are excreting plenty of nitrogen and
probably phosphate as well, the only thing that is not abundant is
Potassium. Now you ask, yeah so, what then, if the plants I want and the
algae all grow in the same environment, then it's a no win situation. This
is not true, there are differences. All plants are not the same. Algae are
efficient feeders, they are also very advantageous growers, adapting to
use what is available. But if the required nutrients are made unavailable
to the algae well, they go away. There are however, certain methods that
allow the higher plants to out compete the algae for available food
sources, and this is what we want to take advantage of in our fight
against algae. That brings me to my next statement.
Use the higher plants to out
compete the algae.
If we cater the water parameters to favor the higher plants they become
nutrient magnets. The higher plants will consume the majority of the
nutrients leaving little behind for the algae to survive. Now that is not
to say there will be no algae, but without enough food, the algae will be
held in control. There is always going to be algae in the tank, it came in
with the plants, but proper management can keep it at bay. Lets take a
look at the main nutrients.
|2-4 watts per gallon.
||Trace to 25ppm
|This has a
broad range for interpretation. Full spectrum is the best, but
intensity is more important. See our lighting
section. More then 12 hours is unnecessary.
pretty straight forward. The ammonia and nitrite levels should
always be unmeasurable. And the Nitrate levels should be kept
nitrate. Since this and nitrate are your two main concerns, keep
this on at a minimum. Trace amounts are all that's needed. And it
is the easier to control.
has never been associated with algae blooms. Therefore there is no
real hard number here. Keep the levels up, but there is also no
real test kit for this one either. I dose it regularly.
mix recommended is in the PMDD
link. The measure for all trace elements uses Iron as an
indicator. Keep the Fe level below 0.1ppm or algae will like you
With the above table in mind the general recommendations can fall into
place. Ok, in a plant tank we will have lots of light. This is a given and
needed to keep the plants happy. So there is no leeway there right, wrong.
Remember details are key, and therefore we can make some minor adjustment
here that will favor the plants. Again algae is very opportunistic and
will absorb just about any form of light. But plants predominantly use
blue and red. The orange, yellow green and indigo are useful as well, but
not as important. The plant lights, gro-lux, and other "grow"
bulbs are mostly red and green and shed a funny purple hue. Now cool white
and a lot of cheap aquarium tubes are heavy in the green spectrum as that
is one of the best we can see. However plants are green and that means the
majority of the green light is reflected and the others absorbed. So the
use of a nice full spectrum light and a Plant light are of a little help
here as most of the light works for the plants.
I like to discuss (N)itrogen and (P)hosphate at the same time as they
are inter related when it comes to algae control. If our plants were grown
emersed (above water) we wouldn't care, but they are not. If we didn't
keep fish, we could control our dose of N & P, but who doesn't keep
fish. Some keep very small populations of fish to keep their N & P in
check and then control their additions. Here is where the fish only people
have their issue too. Outside of the fact that they can always turn off
the lights, fish only tanks generally have a ton of excess N & P. And
in the fish only case we can do increased water changes. But in a plant
tank we already do them every other week right?:) So what's next. Get the
plants to eat the excess. Or is it excess. Well if there is algae it is an
excess. Balance is what you want. You need to get the plants to consume
the available nitrate and Phosphate and keep the levels in check such that
there is not an excess. Now the other fact is that if you keep at least
one of them in check you will go a long way for algae control. If either N
or P is limited, in short supply then the algae will be hurting for food.
Now if you have enough light and there is not to many fish, and the
nitrate levels are up, the PMDD methodology calls for an increase in
15 Helpful tips towards algae free plant tanks.
So Potassium(K). I start with the recommended dosage as called out in the
PMDD recipe then augment from there. The baseline recipe is a good start,
then you can add more as needed. And remember an excess of K dose not lead
to an algae bloom. What the exact concentration does to the tank I am
unsure of as of now. But my method has been working well for a few years
now. You increase the K dosage as needed to reduce the nitrate levels.
Although I find the PMDD baseline to be a pretty good value, my only real
increase is during water changes. I add about 1/8 teaspoon per 10 gallons
of replacement water. Now there are other fertilizer methods and they will
all call for slightly different approaches. But the basic call for
potassium is something that seems to be somewhat overlooked in some
fertilizers. A lot of liquid fertilizers are trace mixes and lack
Trace elements are the last factor. Most mixes used have the correct
balance for all the trace elements. This way we can monitor one element to
gauge the correct concentration of the others. Basically the assertion is
that if the iron levels drop then it was consumed and the other
microelements will be consumed in equal proportions. So we monitor the Fe
levels and maintain them bellow 0.1ppm. Also if there is an excess of any
one trace element left over it's concentration will be reduced through
regular water changes. So the trace element management is pretty simple. I
myself only measure Iron if I suspect an excess for one reason or another.
But I also watch the color of the red pigment in plants to indicate
enough. But with algae control we are more concerned with an excess of
iron. Although as I have said before, balance is key. A lack of
microelements or any one of them can stunt the growth of the plant and
lead to a decrease in the uptake of other nutrients leading to an excess
of something like nitrate. Now this reminds us that balance is concerned
with all nutrients, not just one.
So a balance means you will need to pay attention to all these conditions
at the same time. That sounds like a daunting task, but once the balance
is achieved it is not a very fine line that is easy to loose. You can
maintain a tank without measuring all these parameters all the time. Once
the tank is there and you get an algae outbreak you may need to measure a
few parameters to get an idea of the problem, but with the
interrelationship of these ideas in mind the solution will be obvious.
Keeping all the values in check will all but guarantee success. But
usually the balance is not an immediate thing but something that requires
a tank to break in for a few months. The break in period is the most
crucial. After that following a few guidelines will mean a controlled
Lets cut to the chase. What does this all mean. Well like I said the key
here is nutrient control. A balance of all the details that will produce
an environment which stimulates the plants and hopefully allows them to
consume enough excess nutrients to keep the algae at bay. Therefore I have
a few recommendations that will help achieve this condition. Doing all of
these is not necessary, but the more satisfied the better the results.
2-4 watts of full spectrum light run for about 12 hours a day. A
Timer is helpful to maintain consistency.
fish load, feeding schedule, and water change schedule that will
keep the NO3 levels below 25ppm.
levels should be minimized. There is plenty of P in fish food and
additions are rarely needed. Watch out for pH buffers, many use
one of the most overlooked additions. Adding K on a regular basis
will increase the plants ability to uptake other nutrients.
elements are very helpful. In low light conditions plant uptake
rates are slowed and it can be easily overdosed so monitoring of
Fe levels are highly recommended until the hobbyist becomes
the substrate is advantageous. As long as there is no UGF,
additions of Nitrogen and Phosphate to the substrate may keep them
out of the water column and available to plant roots.
|The use of a
phosphate absorbing resin in the filter in times of nutrient
imbalances can be helpful.
incorporation of fast growing plants especially in the beginning
will help consume excess nutrients keeping the water born food
||The use of
substrate additives will produce a favorable environment for the
plants roots. Laterite is highly recommended but there are other
changes ever two weeks help dilute excess nutrients and maintain a
clean environment. To many water changes will not allow the water
to stabilize and can be just as bad. *
(see note below table)
your tap water conditions can help you decide if any other
additives are needed like Calcium or if you need to leave
something out of your fertilizers.
of CO2 can be a major advantage to stimulate plant
growth. Additional CO2 will substantially increase
additions of liquid fertilizers assure a consistent availability
of what the plants need. Dosages need to be watched so not to
overdose, but Fe can be made unavailable in only 24 hours.
cleanliness can be very helpful. The prompt removal of dead and
dying leaves and other debris can help contain the release of
eating army can help keep the algae in check. There will be algae
and fish snails and shrimp can help control it.
* By Discus fish you have to change water
every week a minimum of 30%.
Sorry, you didn't get one simple answer like more water changes or a
different food or and algae killer. But that is because this approach does
not treat the symptoms, it helps eliminate the conditions that cause
algae. When we keep the water born nutrients limited, especially phosphate
and nitrate algae will have a hard time getting a foothold on your tank.
And the best, natural, long term, low maintenance approach for this is
make the plants grow like mad. You need to control the input of plant
nutrients including and most importantly the ones provided by the fish.
The best environment for the plants yields a great opportunity for algae,
so limiting the N or P in the water column will greatly help in limiting
the algae growth. Also to be considered is the presence of Fe. Iron can
almost spur on algae as fast as an excess of N & P, but without the N
& P the algae will still have a hard time Fe or not. If a plant
doesn't work for you, try another. A tank full of hard to grow plants will
undoubtedly end up with algae. Start with a lot of fast growers and then
over time replace them with slower growers and those that may be harder
for you to grow. But if you have enough fast growers, one or two problem
plants will not bring about algae. Learn to be observant of the tanks
condition. If you see a possible nutrient imbalance in the tank and can
identify it early you will be well ahead of the game.