
Diana Walstad - 50 gallon tank
Dear Mrs. Diana, thank you for volunteering your time to this interview so you can share your knowledge and expertise with us.
First, tell us a bit about yourself. What is your background in the world of aquariums, how long have you been in this hobby?
I was born in 1945 to a family that always had aquariums and ponds. I kept frogs and Mosquito fish as a child and then moved on to gouramis and guppies. However, I left the hobby for several years after a Camallanus (parasitic worm) outbreak in some of my cherished guppies. I could not get rid of this parasite.
Meanwhile, I received a degree in Microbiology and was working as a research technician in several medically related fields. In 1988, I decided to try keeping aquariums again. Only this time, I had enough research experience, determination, and money to try new methods and investigate problems. For example, when the dreaded Camallanus worm once again infected my guppies, I consulted a fish veterinarian. This time, I got the medication and treatment plan that worked to successfully eradicate the parasite.
Your book Ecology of the Planted Aquarium was the culmination of many years of work. Could you please tell us in brief what first inspired you and what was your original goal for the project?
Believe me, there was no plan to write this book. When I started keeping tanks again in 1988, I was determined to have a planted tank. All past attempts had failed, so this time I tried something different- put soil in the tank. I was inspired by a 1988 magazine interview of Dorothy Reimer. She described getting spectacular plant growth using potting soil.
When I too used potting soil and got spectacular plant growth, I was converted. I also noticed that my fish were doing very well in these tanks with minimal tank maintenance. In 1991, I submitted an article about "my method" to an aquarium magazine. The article was promptly rejected. I then decided to write more substantive articles on scientific information that I had started finding in university libraries. I had no trouble getting science-based articles published in various aquarium magazines.
Meanwhile, I noticed that the university libraries had exciting information that was not in the aquarium hobby. When I found Robert Wetzel’s Limnology, I knew I had struck gold. I realized that many of the concepts he described about lakes and streams could apply equally to aquariums. I was entranced by what I read in his book and the scientific papers he cited. Whenever I had free time, I visited biology and botany libraries of the three major universities in my area. These wonderful libraries have a treasure chest of scientific journals on water chemistry, aquatic plants, etc.
Diana Walstad - pond
I also started an Aquatic Ecology Index of the scientific papers, which made writing the book later doable. I carefully subject-indexed every paper before it went into my filing cabinet. For example, one paper might discuss metal chelators and humic acids from the perspective of iron nutrition, while another paper would discuss them in terms of "acid rain" and reducing metal toxicity in fish. I would subject-index both papers under "chelator" and "humic acids". Eventually, I could go to my Index and quickly find many articles with information on metal chelators and humic acids. The Index is now over 100 pages long for the 800 plus papers I have read and indexed. Without the Index, a book with so many seemingly unrelated topics would have been very difficult to write.
At some point, I decided I could mesh all the articles I had written on so many unrelated topics into a book. It was worth doing.
For someone who is unfamiliar with your method, please describe the main principals of your approach towards Natural planted tanks?
My method mimics nutrient-cycling in nature. It uses plants to keep the fish healthy by recycling fish wastes. In turn, fish and ordinary soil provide the nutrients that plants need. Aquatic plants can play an important role in the aquarium. For example, plants keep algae in check, take up toxic ammonia, and oxygenate the substrate. Plants reduce the need for frequent water changes and gravel cleaning while still keeping the fish healthy.
However, many common aquarium practices (frequent cleaning, gravel-only substrates, vigorous aeration, etc) do not allow plants to grow well. Thus, many hobbyists have trouble growing plants. They do not appreciate the role of decomposition in providing nutrients and CO2 to plants, so they keep their aquariums too clean for plants. They do not understand the value of having soil in a tank, so they try to grow plants in pure gravel. In essence, they do not understand the interaction between bacteria, soil, fish and plants.
Using my method without understanding the interactions can lead to problems. For example, hobbyists use soil in their tanks in order to duplicate my method. Yet, they do not understand soil chemistry, so they make the soil layer too deep. The plants die and algae takes over. These hobbyists do not understand that soil is vital for good plant growth, but a soil layer that is too deep can become severely anaerobic and kill the plant’s roots. They do not understand that there is a temporary period of soil instability in a newly setup tank that warrants frequent water changes. All this I have carefully explained in my book, but many people just want to duplicate a method blindly without reading my book first and learning about aquarium ecology.
Diana Walstad - 5 gallon Betta growout
Is it possible to keep an aquarium with no technology at all, the one which will not turn into a swamp in a month or two?
Absolutely. One only has to look at rivers and lakes to see that a swamp is not inevitable. However, my tanks all have some technology. They all have heaters and strong artificial lighting (window light is not enough). I have filters or aerators to create mild water movement. This speeds up decomposition and the recycling of fish wastes into plant nutrients and CO2.
Almost all aquarists use some kind of water conditioner to remove chlorine from tap water before the regular water change, even those who try to keep extremely low-tech aquariums. Are there any, even smallest negative effects of these products in a balanced planted tank?
I do not think so? I cannot imagine that a small amount of sodium bisulfite (if that is what we are talking about) would hurt anything.
Lets talk about plants a bit. What plants species do you have in your NPT (natural planted tanks)? What kind of plants better adapt to these kinds of aquariums?
Plants that do well over the long-term for me are the Amazon Swordplant (Echinodorus bleheri), Echinodorus major, Echinodorus tenellus, Echinodorus "Ozelot", Sagittaria subulata, and Sagittaria graminae for fast, quick growth. I think that the Amazon Swordplant is a big help for preventing algae in large tanks. Anubias nana, Cryptocoryne wendtii, Cryptocoryne balansaea, and Java Fern take longer to establish, but once established, they grow well. Best floating plants for me have been Water Sprite (Ceratopteris thalictroides) and Frog Bit (Limnobium laevigatum). Stem plants Bacopa monnieri and Rotala rotundifolia have always done well for me.
Most common aquarium plants will work fine in an NPT. However, stem plants, which cannot use bicarbonates, will only do well in the beginning. For example, Rotala macandra does beautifully for 6-12 months after tank setup and then it will slowly die out. Some plant species just cannot compete in the presence of more robust species after the soil layer releases less and less CO2 and other nutrients into the water.
Interestingly, I have been able to keep more difficult plant species, but only if they are by themselves and not with more robust species. Thus, in my two DSM (Dry Start Method) tanks, I have been able to keep small carpet plants for over a year now. The Hemianthus callitrichoides and Glossostigma elatinoides died out, but the Eleocharis acicularis (Dwarf Hairgrass), Marsilea quadrifolia (Four Leaf Clover), and Hemianthus micranthemoides are doing very well. I would never have been able to keep these 3 plant species in a my main tanks where they would have to compete with larger, more robust plants.
I think hobbyists just need to figure out for themselves what plants work best for them.
Diana Walstad - 55 gallon tank
What do you think about those extremely beautiful exhibition tanks ("Japanese school") that are set not to last but to be destroyed immediately after the show, or after a few photos taken?
Ha! I did not realize that these tanks were destroyed after the show. Planted tanks are easy to set up, but having them last is quite another matter. Aquascaping exhibits help get people excited about keeping plants. That’s not so bad. Some of these people eventually get tired of all the work involved, buy my book, and start keeping NPTs.
Many newcomers have no idea where to begin when it comes to planted tanks and aquascaping. What would you recommend to a newcomer creating his first planted aquarium? What is the basis for creating a healthy planted tank with happy fish in it?
I think that they could start by reading my article Small Tanks for Pet Shrimp (see end of interview for where it can be obtained). Beginners can start out with a small, inexpensive tank. With a small tank and shrimp, they can learn how to work with soil (this is not as easy as it sounds). They will not have to deal with fish diseases, which are all too common in the aquarium hobby. They will learn which plants do best under their soil, lighting, and water conditions. If the small tank succeeds, they will also have a nice supply of acclimated plants to use for a larger tank.
The basis for creating a healthy planted tank with happy fish requires creating good conditions for plant growth and avoiding fish diseases. That’s a big challenge for a beginner. A small shrimp tank is an easy way to start.
Diana Walstad – Two Gallon Shrimp
What is the main objective of your book? What do you hope people will learn from it?
I hope that hobbyists learn to appreciate plants as more than just decoration or an aquascaping tool. That they learn how to use plants to keep healthy aquariums with less effort and expense.
Many of the concepts for NPTs pertain to the natural world. Therefore, aquarium keeping relates to biology, soil chemistry, and many natural sciences. I found this integration extremely exciting. If I found it so exciting, my reasoning was that there must be other people like me that would also love to see it. Fortunately, that turned out to be the case.
Most of your readers are higher educated hobbyists, mostly with academic degrees in natural sciences. But I’m sure you’re aware that there are others who consider your book a heavy reading. Are you planning to write something for youngsters and all those less skilled in chemistry and biology?
No. There are all kinds of "baby" books on keeping planted tanks and aquarium plants. I have no interest in writing such a book (I leave this field wide-open to hobbyists that would enjoy explaining my method to less-sophisticated hobbyists).
I want my book to become a long-term reference book for conscientious hobbyists, biologists and other academic types. That way, they will be able to withstand the continual commercialism in the aquarium hobby and all the silly methods based on "conventional wisdom".
It is sad that all the vital scientific information in my book was not available to hobbyists decades ago. Of course, there is much more money to be made selling gadgets, fertilizers, etc than in promoting natural systems.
Thank you very much Mrs. Diana, it’s been a pleasure and a privilege!
You are entirely welcome.

Is there anything you want to add at the end of this interview?
Yes, thanks for asking. :)
My book’s website has two free articles for download. They are Small Planted Tanks for Pet Shrimp. Although it is suited for beginners, it also discusses setting up a Dry Start Method tank, which may interest some advanced hobbyists.
Managing Mycobacteriosis is about the main disease of tropical aquarium fish—Fish Tuberculosis. The article contains important information on preventing (and managing) mycobacteriosis and other fish diseases. Even beginners should take a quick look, as so often they end up with diseased fish and become discouraged. Nothing takes the fun out of aquarium keeping faster than helplessly watching pet fish sicken and die.
My book’s website is: http://www.atlasbooks.com/marktplc/00388.htm
Diana Walstad intervju - hrvatska verzija ovdje!