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Discussion Starter · #1 ·
I have been using the advice from Mr. Barr's reply from below
plantbrain said:
Back to your tank:
Yes, just follow the advice.
For a 100liter tank with high light:

Add every other day:
1/4 teaspoon KNO3
~1/16" KH2PO4 or 2-3 drops of enema

On the off day, add 5mls of trace mix(TMG, Flourish or equivalent)

Do 50% weekly (or larger water changes)

So 4 days of macro dosing, 3 of trace dosing per week.
This is very heavy dosing and can be scaled back with less light, but it will not harm a lower light tank either.

Make sure you have good CO2.
That's the main issue with your tank.

Tom Barr
I have a 55 gallon tank which is twice this size with bottled CO2 reading 30-35 ppm at the end of the photo period. There is 2.36 wpg and the tank is pretty full but not really with fast growers. I started doubling the above dose (because the tank size is doubled) but have since cut it back to the ¼ and 1/16 teaspoons respectfully. Using a LaMotte NO3 kit I notice that I am reading much higher than the 5-10 +- 1 as listed in the Estimative index. I do perform an approximate 50% water change weekly. I say 50% because I use a siphone drain not measured and I do not know the volume of substrate and driftwood but it is 50% on the glass. Should I change more water to re-set the tank more or lower yet the 4x per week dose amount to bring down the NO3 levels? It averages in the 17.6 ppm range from the LaMotte kit.

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35 Posts
have any fish swimming around in that 55G of yours? That can really affect it. Also if your tank has matured the bacteria that are using the nitrites may also be putting out some nitrates. Just knock off the KNO3 addition a bit and see how things go, IMO.

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5,320 Posts

Tom Barr is certainly well respected in this hobby and the Estimative Index is certainly a good system to start with but I will ask you one question; how are things going? If the fish are healthy, the plants are growing well, and you don't have any major problems with algae then you are probably doing just fine. Unless you have calibrated your nitrate test kit against a known NO3 concentration your test results are probably off.

The first year or two I used various methods of dosing and followed them to the letter. The last "formal" dosing system I used was the Estimative Index. It is a good system and gave me a good basis to start.

Eventually I started looking at my tank, fish, and plants more closely. My tanks are planted maybe a little heavier than average, I have about 2 WPG of light and CO2 on my tanks, and my dosing level is about 2X the "recommended" EI amounts along small supplemental doses of Flourish (Comprehensive) and Iron. I found there was not "magic number" for my aquariums (my NO3 regularly is in excess of 30.0ppm). I do a regular weekly 35% water change. My plants grow well, my fish are healthy (my Corys spawn regularly), and I have minimal problems with algae.


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At this point it is indeed about looking at your plants, fish, inverts, algae... and seeing if it is working at the current dosing. I think most of us started with some sort of 'recipe', then made changes that suited the way we wanted to do things.

If it is working, keep it up!
If there are problems, then alter something. One thing. Let it work for a week or two and see if the problem goes away.
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