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· Registered
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Discussion Starter · #1 ·
Hi all,

I have a tank that measures 130 cm x 40 x 40. It has been set up according to Diana's method. I had watered the potting soil for at least 3 months. After that it has aired for several weeks.
After the setup I have planted the tank with plenty of plant material. Species: Cabomba Caroliniana, Ludwigia Palustris x Repens, Echinodorus Tenellus, Lobelia Cardinalis, Vesicularia Dubyana, Cryptocryne Wendtii, Ammania Gracilis and Bacopa Caroliniana. I have plenty of light above it, even so much so, that the several plant species show oxygen bubbles rising from them and thereby proving that there is plenty of photo synthesis.

I had the setup 2 weeks without any fish and only a couple of shrimps. The tank produced a few green algae tufts that were easily removed by hand. The plants grew very well.

After 2 weeks I put in the fish:

1 couple Trichogaster Leeri, 10 Barbus Tetrazona, 6 Barbus Titeya and 4 Microgeophagus Ramirezi.

All the fish felt at home from the start allthough the Leeri took a little longer since I did not have any floating plants at that moment other than some duckweed.

After about a week I received Pistia Stratiotes that started growing on the spot. It was necessary also since around that time the tank had developed a quite severe case of water bloom. I could hardly see the back of the tank anymore. Nitrate levels were 0 and phosphor levels were 2 mg/l which is quite high according to the literature accompanying the testset.

The algae drove the PH up to 9 and above so I had to do something more than just adding the water lettuce. I put in some filter charcoal and at the other end of the micro jet pump I put a piece of cloth, folded together several times and with some tie wraps I stuck it onto the outlet. Furthermore I took out the lights that have mainly blue spectral rays.

Within 24 hours the water became crystal clear. After about a week and after several cleanings of the cloth it shows hardly any algae signs anymore so I think I have overcome this problem. It showed that the PH became indeed much more stable, ranging from 7.2 in the morning to 7.9 in the evening which is satisfactory to my opinion.

That was a long intro ..... now to my real question.

Reading a lot on the internet of course I stumbled upon the Redfield Ratio (I guess that you all know about it ?!? - if not read

Of course I started testing the tank water again and found the following values:

No3 - 0 mg
Po4 - 0,25 mg

So both are pretty low. The water lettuce must have take care of the Po4 levels in an efficient way.

However, according to the internet readings my Redfield Ratio is way off. However, my plants show excellent growth and I do not feel like changing anything at the moment. Should I be concerned and should I try to raise the nitrate levels in my tank (of course in a natural way as much as i can?)

I cannot find any comments from Diana on RR so I am curious how she and others think about it.

That's it for now. Thanks for 'listening in' and eagerly awaiting your answers.

Cheers Frank

p.s. Diana - thanks a lot - I have the best tank I ever had thanks to your methods !!

· Super Moderator
4,233 Posts
Hello Frank,

Glad your NPT is working out so well.

Scientists have long used Redfield Ratio to track nutrient cycling (especially N) through ecosystems. Redfield Ratio is just a fancy way to say that all living things contain a fairly fixed ratio of N to P to C. I used this concept in my book to show that fishfood will supply N,P,C in a fairly fixed way, because fishfood is made from living things (plant and animal matter). In addition, I extended the concept to other nutrients. For example, all living things need iron, so you can count on the fact that fishfood will contain iron.

That's why I continue to plug fishfood as the best fertilizer money can buy. It contains all nutrients that plants need. AND unlike chemical fertilizers, fishfood nutrients are released in a slow, safe way as the food is metabolized by fish and/or bacteria.

As long as you're adding fishfood, aquariums generally have more than enough N.

It sounds like you've got a well-balanced ecosystem. Plants are taking up the nitrogen as fast as the fishfood provides it. Funny how easy things are when we give Mother Nature a chance!

· Registered
930 Posts
There is an old saying that applies here - It works leave it alone.

Nature is not an exact science. Stop worrying.
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