Okay, I will just quickly summarize what happened. But before that, I will just say that this is for a school science fair, so it's perfectly okay if you think my experiment and results are wrong, I am no pro (I suck at science fairs and this is my third one :P). The results of this experiment are not "final"; future experiments will either prove me wrong or add other stuff to this.
The experiment was conducted in two 5 gallon buckets using floating riccia fluitans as the experimental plant. Each bucket has a submerged Tetra Whisper 10i filter. The light fixture used is a 36" Marineland Dual-Bulb T-12 fixture and the bulbs are 5200K. The amount of water used is 20 liters, I am in Orlando so you can get an idea of the water chemistry here (Florida is basically limestone
). I also added 22 grams of biobale to the bottom of both buckets to have some biological media (yeah, I had no other options). One filter has 100 grams of new Fluval carbon, while the other had a small chunk of cement to reduce flow to approximately the same as the other filter with carbon.
I used 5 grams of riccia in each bucket. My error in this was not drying each portion of riccia equally, so there might be differences in mass when I measured it. The plants are left floating at 12 inches from the light bulb. The location of the experiment is in a shaded area where both buckets get the same amount of light. The light is turned on 10 hours a day
I decided not to do any water changes, so I added fertilizers for only 6 days of the 21 day span of the experiment. I used Wet's Nutrient Calculator (http://calc.petalphile.com/
) with the settings to Estimative Index. I dosed KNO3, KH2PO4, and Plantex CSM+B.
There is no more need to post more specific specifications since I eliminated most of the variables from my experiment. All the buckets are treated the same way in the same manner.
So after 3 weeks here is the result: The riccia's plant overall plant mass was exactly the same in both buckets, both weighed 12 grams; I made sure that they were equally dried this time prior to measuring. But the live mass was different. The bottom parts of the riccia turned black and died while the other is perfectly fine. Other differences between these two buckets are: There are at least 20 times more hitchhiker duckweed in the bucket without carbon than the bucket with carbon. The water clarity of the carbon filtered water is however clear, while the other is slightly tinted yellow. These are the main differences. Other small things I have noticed are that there are snails in the bucket without carbon than its counterpart. There are also more dead insects in the carbon-less bucket too.
REMEMBER!!!!! A bucket is nothing compared to a full planted aquarium. Everything is different. Besides 100 grams of carbon used in a 5 gallon bucket is OVERKILL. And I will stress again that a bucket is not an aquarium; I used 2 liters of Seachem Matrix Carbon on my 21 gallon and no apocalypse happened
. This experiment simply showed that carbon has useful cleaning abilities and that it CAN affect plants, but it would most likely not in a planted tank.
What I got out of this is that it is a really good thing to use carbon in the beginning of a planted tank to remove all sorts of crap from new stuff. I also feel that carbon is most cost-effective when used in small amounts over time to improve clarity and remove odor. Better to use a bit more in the start-up of an aquarium and then cut the amount used so that it would continually filter the water without taking so much expensive trace elements.
When I have time, I want to do this experiment over again but with even fewer variables.
My conclusion: Carbon is not necessary to a planted tank at all as Mr. Barr said. I think it is more of a conditional media which should be used at proper times. The knowledge of using it at proper times comes through experience. An example is thorough clean-up of leftover medicine which water changes sometimes cannot do. But in the end, sadly I have to say that it is personal choice of whether you want to use carbon in their tanks.....sorry for those who are looking for a "this is it" answer......
QUESTIONS? COMMENTS? ANYTHING THAT I MISSED? CRITICISM AND ADVICE WANTED!!!!!!
As with the pictures, here is the tip: unhealthy=carbon bucket