The Planted Tank: Going High-Tech

The Planted Tank: Going High-Tech

Author: Rhonda Wilson

There are many options when keeping a planted tank, and they each have their advantages and disadvantages. You can choose the method that’s right for what you want to grow, what sort of tank you want, and the time you want to put into your tank. You can use your tap water as it is, change it with RO or distilled water, add CO2 and fertilizers, or any combination of the above. Be sure to research what you’re doing first, though, so you won’t be surprised by the results.

It shouldn’t be surprising that the water you use will affect what plants you can grow and how well you can grow them. Many aquarium-plant growers will go to great lengths to try to provide the optimum growing conditions for their plants. I tend to take the easier approach, and I grow the plants that do best with my tap water. This isn’t just the case for plants, but fish too. I raise livebearers that come from waters south of the border, similar to the water we have here in Arizona.

On the other hand, I do like to experiment. And though I’ve swapped some of the smaller tanks in my fishroom out for larger ones, I still have about 70 planted tanks to play with, so I do have a little room for experimentation.

It’s always been frustrating for me that Java ferns have been somewhat difficult for most of us down here in Arizona to grow because of our tap water. And although I could grow it like crazy in Montana, water sprite (Ceratopterisspecies) just wouldn’t do well for me, and the same goes for most of the other people I’ve talked to around here either. My water comes out of the tap moderately hard and at over 8.0 pH, settling down to about 7.8 in the tanks. I finally decided to start playing with the water a bit to see what would happen.


I started with a 20-gallon tank that was already set up. As I had gotten lucky in my recent garage sale hunting and found a small portable RO unit, I replaced some of the water with RO water to bring the pH down to 7.2. Since we live in the desert and I worry about wasting water, I can set the RO unit up so all the waste water goes to my plants in the yard. Later I had another idea. In the summer, which can pretty much last nine months of the year, we use an air conditioner. The air conditioner also produces water, which is basically like distilled water, it pulls it out of the air, and so I started collecting water from the air conditioner and use that during the warmer months. It’s also great for topping off tanks, since I can set a hose up to it directly and dribble the water in to my tanks.

Regardless of where the water came from, my goal was to lower the pH and hardness and see what different results I would see, if any, in my attempts to grow some of the “easy” plants that didn’t like my Arizona water. The half-and-half solution was just the trick I needed for getting the Java ferns to grow, but the Ceratopteris still didn’t do very well. Still, I was happy to be able to finally get decent Java fern growth, and I did another 20 gallon with the half-and-half method and had equally good success with the Java ferns in that tank as well.

It’s not surprising that your water will affect the plants that can grow in it. In her book Ecology of the Planted Aquarium, Diana Walstad writes about the change in plant species along the Carolina river system. Different species live in the soft-water areas than in the areas where hard water is prevalent. She mentions that hard-water species are more likely able to use bicarbonates, and the soft-water and amphibious species need CO2. She also mentions a Japanese study that had similar results.


Most of my resistance to setting up a tank with CO2 has been my concern for the well-being of my fish, though the extra work wasn’t really making it all that appealing for me either. I finally was convinced to give it a try during the 2006 Aquatic Gardeners Association Convention. It had been mentioned to me that everybody else was doing it, and since I wrote about planted tanks I should try it too. It was a valid point. But the thing that helped finalize my decision was the talk by Ole Pedersen from Tropical of Denmark. He had slides with the figures for the CO2 rates in naturally occurring waters in Europe, and some of them were even higher than the levels suggested for aquariums.

I was convinced to give it a try. I had purchased quite a few harder-to-find plants at the convention, and I really wanted to get them growing before trying them in my other tanks.

I set my CO2 tank up with potting soil for the bottom layer of the substrate, then a thin layer with old black sand from another tank to keep the potting soil firmly down, and then a final layer of black gravel. There are several pre-mixed substrates available at many pet stores, but I had potting soil on hand, and I had previously used compost in pots for several of my aquatic plants with good results.

I purchased a small CO2 unit at a pet store. These use basically the same methods as the do-it-yourself models, but a little nicer looking and I didn’t have to make it. They are reasonably priced. Some of the other CO2 methods, using tanks of the gas, can be quite a bit more expensive, though they also can give you more CO2. They also don’t require being set up every couple of weeks when the yeast factory burns out.


With CO2, your plants will grow much faster. At first I was having a bit of trouble with algae and green water but that has mostly cleared up. Water changes twice a week were necessary at first, but after a couple months weekly water changes seem to work.

For lighting I’m using two fixtures, each with two T-5 bulbs. I tried using just one fixture but found it didn’t light the whole tank front to back, and it didn’t seem that all the plants were getting enough light. So I added a second fixture and it really seems to have helped.

I’ve been dosing the tank with a variety of fertilizers. I had a little cache built up from aquarium club raffles. The plants use up the nutrients quite quickly in a tank with good lighting and CO2, and I can definitely notice problems in the plants when I stop dosing. Different plants show different issues; curled leaves, changes in color, and smaller leaves are some of the problems that crop up when I don’t keep up with at least weekly water changes. I’ve also found the CO2 unit lasts about two weeks before it starts slowing and needs to be changed. All this means this tank is a lot more labor intensive than my other aquariums.

All this extra work does produce incredible plant growth and allows me to grow plants that I didn’t do well with before.

The fast growth adds even more work, because you have to keep it trimmed. Weekly trimmings are really necessary to keep it looking good. If I wait a couple weeks it starts really getting out of hand. What has been the most amusing to me is the Glossostigma. This is a plant that I tried several times with only very moderate success. In the high-light, regularly fertilized, CO2 tank, though, it truly grows like a weed, easily covering everything else—including itself.

Some of my local plant-club members have taken this all much further. Roy Deki, one of the founding members of Arizona Aquatic Plant Enthusiasts (AAPE), uses RO water and pressurized CO2 in his tanks along with special substrates, fertilizers, and lights. All the extra work he does pays off with beautiful tanks. Roy’s tank, named “Mizu Ikebana,” was the second place winner in the 2006 AGA Aquascaping contest for the 70-liter to 200-liter aquarium category. Roy’s prize-winning tank is 24 gallons and is outfitted with 6700k, 72-watt power compact lighting. He uses an iron-rich, pourous clay substrate with silica sand in the foreground. The plants include Anubias nana, Blyxa aubertii and B. japonica, Cryptocoryne petchii, Rotala rotundifolia, and two types of moss. It wasn’t hard to talk Roy into sharing a few of his photos for this month’s column.

Since starting my first CO2 tank I have added CO2 on a second tank—my 50-gallon tank in the living room. I just have one small CO2 unit on it, and I haven’t added anything else to the tank. I have seen better plant growth in it and have added Glossostigma and two species of Ceratopteris to this tank, and they are growing well.

I am thinking about adding a couple DIY units with old one-liter soda bottles to a couple other tanks. It is fun playing with the CO2 in some of my aquariums, though I still am not interested in using the pressurized tank setups, and I have no intention of using CO2 for all the tanks in my fishroom. I don’t think I could possibly keep up with all the extra work, and I still don’t trust the CO2 enough to use it in the same tank I keep my rare and much loved livebearers.


There are many ways to have a planted tank. You can grow many plants in a simple setup with reasonably good lighting and tap water, or you can change your water and add CO2, special substrates, fertilizers, or more lighting, depending on what plants you want to grow and how much work you want to put in to your tanks. No matter what your goals or interests are, or the time or money you have to devote to your planted tank, the aquatic plant hobby offers choices for everyone.