# Question about the importance of soil (newbie here)



## Elliabel (Jun 3, 2009)

Hello everyone my name's Cat.
I just finished doing a project for high school and I got quite interested in the NPT approach. I have read some of the posts here including the ones by Diana Walstad. I am thinking of setting up a NPT (it would be my first tank ever) but I am confused about the role of soil. I know it provides nutrients to plants that have roots, but does it also provide the water column with nutrients?

What about pants that don't need to be planted such as frogbit, elodeas, watersprite etc? Do they get nutrients/CO2 only from fish waste or they also benefit from the soil? What would happen if I set up a tank with plain gravel (no soil) and a bunch of floating plants that don't need to be planted to live? Would it still be a NPT tank or would I need to perform regular water changes?

Sorry if my questions seem basic but I tried to find Diana's book at B&N and Borders but it was sold out. I want to buy it online but I have no credit card, I am in the process of borrowing one. In the meantime I hope someone here will be kind enough to answer some of my questions,
Thanks!


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## Evil-Lynn (Apr 6, 2009)

That's a good question. I am terrible at chemistry, but if the set up you are inquiring about does work I would assume your plant choice would be very limited. I have a nano tank that I set up the following way: I added one inch of unfertilized potting soil, then an inch of regular gravel. I added hornwort, elodeas, vallisneria, anubias and a weird moss I was never able to identify. The hornwort was floating but was losing its leafs badly. Supposedly they take some time to adapt but I am not patient and the needles were causing too much of a mess.

The same thing happened to the moss, which was also unplanted. I think not knowing how to care for it had a major role in his demise. Anyhow, the Anubias are doing OK, but the Vals and Elodeas took off quite nicely taking over the tank. Only the Vals are properly planted, so to answer your question, nutrients in NPT are found in both the substrate and water column. Perhaps someone else can explain how this works better?


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## dwalstad (Apr 14, 2006)

Elliabel said:


> I know soil provides nutrients to plants that have roots, but does it also provide the water column with nutrients?
> 
> **Yes. My book, p. 131.
> 
> ...


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## Elliabel (Jun 3, 2009)

> **Good growth of floating plants will purify the water (remove ammonia). Just don't use a thick layer of gravel that will generate ammonia, nitrites, and hydrogen sulfide.


Thanks for your rapid reply! So if I use a thin layer of gravel I won't theoretically need to perform water changes? How would you define thin? less than one inch?
I'll check my local public library for your book, thanks for the suggestion.


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## Evil-Lynn (Apr 6, 2009)

I actually remember reading on an older thread that you need to perform regular water changes if you are using just plain gravel and no soil. That is to avoid excess organic waste build up at the bottom of the tank which can be toxic to plants, fish and can cause algae growth. In fact, I read that BGA thrives in gravel that hasn't been vacuumed in awhile and people manage to keep it under control when they vacuum the gravel on regular basis. Vacuuming implies a change of water...


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## Elliabel (Jun 3, 2009)

I reckon that would make sense. I assume then, that soil has a way of eliminating the excess organic waste that falls at the bottom of the tank on its own?


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## Evil-Lynn (Apr 6, 2009)

Indeed,
I recommend you read the following sticky, notably Javalee's post: http://www.aquaticplantcentral.com/forumapc/el-natural/26458-what-el-natural-step-step.html
It explains how soil is necessary for production of beneficial bacteria, nutrients, CO2, etc that promote healthy plant growth. Most important, it inhibits the production of toxic gas that can be harmful to your fish, invertebrates and plants. Thus, if you are not planning to use a soil based substrate, I'd recommend you vacuum your gravel once a week. This will remove some water so you don't need to perform an extra water change. Unless of course Diana suggests otherwise.


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## dwalstad (Apr 14, 2006)

Elliabel said:


> Thanks for your rapid reply! So if I use a thin layer of gravel I won't theoretically need to perform water changes?


Yes. I have set up tanks with just a scattering of gravel and sand on the glass (1/4 inch?). That way, the substrate stays aerobic, but you've still got some attachment sites for helpful bacteria. [A thin gravel/sand layer is better than bare glass.] The bacteria in this aerobic environment can recycle the fish wastes that inevitably sink to the bottom. Also, I found that the mulm that accumulates in these setups has a lot of nitrifying activity.

Now, all you need is good plant growth. I added potted and floating plants to my setup. If your plants grow well, they will keep the fish healthy without the need for frequent water changes.


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## Evil-Lynn (Apr 6, 2009)

Gosh, that's why I love coming to these boards, you learn new stuff everyday 
So what I gathered so far is the following:

-1 inch unfertilized soil + 1 inch of plain gravel = good.
-more than 1 inch of soil and more than 1 inch of gravel = bad.
-more than 1 inch of plain gravel - soil = bad
-less than one inch of plain gravel - soil = good if you have floating plants.

It's all about keeping your substrate aerobic and promoting healthy plant growth.


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## Elliabel (Jun 3, 2009)

I agree Lynn, and thank you for that brief explanation on what to do and what not to do. I understand more things now.

Diana, you actually motivated me to set up a tank like the one you just mentioned. I have this 10 gallon tank, I will add less than one inch of plain gravel, no filter just a powerhead, some white light and some access to indirect sunlight, and I will add a bunch of plants that don't need to be planted to grow. I want a small population of black mollies to start. Wish me luck!
Cat.


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## Evil-Lynn (Apr 6, 2009)

Sounds good to me. Just remember that not all floating plants need to be kept floating. You can attach some to the bottom of your tank. In case you don't want your plants to look like a big floating green mess ...:fencing:


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