# [Wet Thumb Forum]-Do non-rooted plants grow well in a soil-based aquarium?



## askindc (Mar 30, 2005)

I am very fond of many non-rooted plant species, and I'm currently growing (i) three varieties of Java ferns, (ii) Anubias berteri (var. nana), and (iii) Brazilian pennywort in a lowlight (ca. 1.3 wpg) Eclipse 6-gallon aquarium equippped with its usual filter and Bio-Wheel. The first two are resting and growing upright on a 1.25-inch deep, all-gravel substrate, and the usually much faster-growing pennywort is growing as a floating plant near the water's surface. All three species are doing extremely well under those aquarium conditions. However, after reading Diana Walstad's very interesting, thought-provoking and well-written book, I have begun to think strongly about trying to set up a successful small aquarium (in addition to my current one) that has a soil-based underlayer substrate. My only concern, however, is whether the three non-rooted plant species I like very much would do well in that type of environment. Unfortunately, in at least two places in her book (the bottom of pages 136 and 139), Ms. Walstad mentions that soil substrate deterioration is likely without rooted plants, and that soil-based substrates without rooted plants will degrade with time (both, I assume, because of the development of strongly anaerobic conditions). So, I'm writing to inquire about how successful my fellow aquarists have been in growing the above-mentioned, non-rooted aquatic plants in their soil-based aquaria. If the soil-based approach is not successful with those types of plants, I probably will limit myself (in my new soil-based aquarium) to trying to grow the various, very beautiful Cryptocoryne species. Thanks very much for the benefit of your experience and for any suggestions you may have for me. Also, thanks Diana for writing your fine book! Your approach definitely was a "learning experience" for me.


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## javalee (May 8, 2006)

I would grow both if I were you----cryptocorynes and non-rooted plants. I have anubius, java fern, moss, hornwort, salvinia, water lettuce and duck weed all doing fine now in addition to many rooted plants in my soil substrate tank.

Remember though, that the role of the non-rooted plant in a Walstad-style aquarium is to remove excess nutrients from the water to prevent algae. So they are utilitarian, and mine sometimes DO use up all the water nutrients since no fertilizers are added to this type of tank. When this happens (especially after water changes), the new and old leaves turn yellow on the floating plants and non-rooted plants. Then I just thin them out until the remaining green-up again.

Your local tap-water and the amount and type of nutrients that your soil will leach will determine how well non-rooted plants grow. But, yes, mine do just fine. Maybe not as lush as a fertilized tank, but just fine.


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## askindc (Mar 30, 2005)

Thanks very much for your kind and helpful advice, javalee! I've never tried growing any of the many very attractive Cryptocoryne species. However, when I set up my first test tank (probably 6-12 gallons and not more than 1.5 wpg, later this year) containing a soil-underlayered substrate, I think it will be exciting and logical to grow them together with the other two low-light species mentioned in my original query. Hopefully, the Cryptocoryne will take care of the requirement for rooting plants, and the non-rooting Java ferns and Anubias will grow slowly enough so that they will do well in the same low-light, soil-based environment. Of course, since all three are relatively slow-growers, I realize that I also will have to include (at least in the beginning) one or two fast-growing species, in order to suppress the growth of algae. Right now, I'm leaning toward Brazilian pennywort and/or water sprite because I've had good luck with them in the past and they are easy to obtain. 

Yesterday, I started my first "bottle test" with some "Schultz Professional Potting Soil Plus for African Violets & Flowering Plants." So far, the preparation is behaving well (no turbidity or color), but I will be observing it and testing for pH changes and the presence of ammonia, nitrite and nitrate during the next couple of months. Also, while that mixture is "cooking," I will try to obtain and test some less nutritious potting soils. Do you have one that you particularly like? 

Thanks again for your help!


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## askindc (Mar 30, 2005)

This morning I discovered and read previous messages exchanged by Whiskey and Diana Walstad (on 4/3-4/8/05), which I think are pertinent to answering my question which started this short thread. Whiskey inquired (on 4/3/05) whether it would be O.K. to convert a high-tech aquarium, in which he had a very heavy growth of large Java ferns, to a low-tech tank. To quote him: "It is like a forest. If I keep this large group of ferns, will I have problems? I worry because ferns don't have roots or anything to keep the soil good under them and from becoming very anaerobic. I have no way to test redox, and I don't want to shoot myself in the foot. Is this something I need to worry about? Or am I overthinking things?" 

Diana Walstad replied (on 4/4/05): "I have bare, unplanted areas with soil underneath and no problems. Remember that there are many unplanted lake areas, and the fish do fine. So it is certainly possible. Despite what I wrote in my book, I now believe that it is not necessary for plant roots to keep the substrate aerobic. Moreover, once the soil settles down in an established tank, it contributes to tank health. For example, when I did my bottle experiments (soil and water only), the soil bacteria removed ammonia. The only scenario that would cause problems would be potting soil substrate fertilized with sulfate- or nitrate-containing fertilizers. Nitrates will become toxic nitrite. Sulfates will become toxic hydrogen sulfide."

So, because of the information presented in the above exchange, and the information contained in javalee's post, I'm currently encouraged that rhizome-bearing, non- or poorly rooting plants (e.g., Java ferns and Anubias species) may be grown successfully in soil-underlayered aquaria, without problematically destabilizing the aquatic environment. However, since I'm not sure whether this can be done in the total absence of rooted plants, I will try to see if I can do that when I set up my first test tank later this year. In any case, I assume that one would have to watch non-rooting plants carefully, to make sure that they are obtaining enough nutrients from the water column. Perhaps some modest, occasional supplementation with an appropriate liquid fertilizer may then be necessary?


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## dwalstad (Apr 14, 2006)

The one thing I'm not understanding is why you want to add soil at all? It sounds like you have good plant growth and that you are happy with growing non-rooted plants. I've had tanks with just Java Fern or Anubias on rocks and driftwood. They are nice, and the fish are easily caught. 

My only advice for this type of tank is that you use a slightly thinner gravel layer-- maybe a 1/2 inch? That way it won't go anaerobic and generate substrate toxins that might hurt the fish. You could try growing a Crypt or two in pots with soil.

While I think have soil in tanks is great, I wouldn't add it just for the sake of adding it.

Maybe I'm missing something here??


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## askindc (Mar 30, 2005)

Dear Diana,

Many thanks for kindly taking the time to reply to and advise me concerning my recent postings to the El Natural Forum. It's quite true that I've been very satisfied with growing various attractive, "low-light," rhizome-type plants in gravel-only substrates. However, even though I would like to continue using that approach, I also would like to experiment with growing them, alone or together with other attractive low-light plants (e.g., Cryptocoryne species), using your scientifically sound, soil underlayer-based approach. I'm a long-time biomedical researcher (Ph.D. [Microbiology] received from the University of Michigan in Ann Arbor), so using new techniques and comparing the efficacy of various approaches has probably always interested me in my vocation and avocations.  I send my best wishes for your continued good health and success with your valuable and interesting research. Thanks again for writing your book. Receiving it was an excellent early birthday present from a friend who knows that I like to learn about and try new things.


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