Aquatic Plants


CO2 Measurements and the Siesta Regimen

Diana Walstad (2015) 

Carbon dioxide (CO2) levels in natural ecosystems often limit submerged plant growth. CO2 levels fall in the morning during rapid plant photosynthesis and are depleted around noon. They are recharged at night by the respiration of fish, plants, and bacteria. The cycle repeats itself the next day.

In 2009, I decided to see what the CO2 levels actually were in my aquariums, which depend solely on natural sources of CO2. The resulting data was more interesting and useful than I expected. I found that CO2 levels were remarkably reproducible day-to-day and week-to-week. Each tank seems to have its own daily pattern of CO2 uptake and regeneration.

I used CO2 measurements to gauge how my plants were actually doing. I gathered evidence suggesting that a Siesta period—lights off for a few hours midday—might benefit the plants. I learned that window light—contrary to my previous assumptions—was not fueling that much photosynthesis.



Diana Walstad (2014)

Ammonium and nitrite are detrimental to fish health. 1 Most hobbyists rely on filters (i.e., “biological filtration” or nitrification) to remove these toxins from the water. They do not consider using plants. Even hobbyists with planted tanks underestimate plants in terms of water purification. For they assume that plants mainly take up nitrates as their source of N (nitrogen).

However, the truth is quite different. Scientific studies have shown repeatedly that the vast majority of aquatic plants greatly prefer ammonium over nitrate. Moreover, they prefer taking it up via leaf uptake from the water, rather than root uptake from the substrate. Thus, plants can—if given the chance—play a major role in water purification. They are not just tank ornaments, aquascaping tools, or hiding places for fry.


Small Planted Tanks for Pet Shrimp

Diana Walstad (February 2010)

Setting up a planted fish tank is littered with pitfalls. Newly purchased plants have to adapt to a new substrate, lighting source, and water
conditions. They may have to adapt to the submerged condition and grow new leaves. Chances are some plant species will not survive. Algae may become a problem. Fish add another layer of complication. Sometimes newly purchased fish become diseased, and hobbyists add chemicals that injure the ecosystem.

Small bowls for shrimp are much less prone to problems—and frustration. In this article, I describe two ways to set up small planted tanks for pet shrimp. The Bowl Setup is quick and easy. The Dry Start Method is more complicated and less tested, but it has some major advantages over the usual (submerged) start-up. 


Native Plants for Aquaria


Plants have been popular in aquaria for a while, they can add greatly to the aesthetic appeal of aquaria & stop fish tanks from just looking like a “cube of water”.   Some of the more extensively planted aquaria are quite beautiful in their own right & they can represent a entire ecosystems in miniature.  These carefully designed & crafted planted aquariums are often referred to as aquascapes. 

The growing of lushly planted aquascapes has become more accessible in recent years, due to much of the required hardware becoming cheaper and more widely available.  The requirements for growing plants in aquarium conditions is also much better understood.  High quality lighting, aquatic plant fertilisation (including CO2), engineered plant substrates and suitable filtration are all readily available.  This equipment is also much more affordable than it was a few years ago.  This all makes it possible for most aquarists to easily produce very attractive underwater gardens.