Photo: Red Mangrove tree in the plant filter.
One aspect of our hatchery systems we use to raise fish that always seems to fascinate hobbyists when I speak at fish clubs is our plant filtration system. Goliad Farms exclusively uses plant filtration designed by us through trial and error. We have no carbon or mechanical filters. For a detailed description of our plant filtration, see the article by Charles Clapsaddle in April 2010 issue of Tropical Fish Hobbyist magazine, “Plant Filtration—No Water Changes.”
Our plant filters in our two large greenhouses (about 3,000 square feet each) consist of three main stages. Our smaller greenhouse (about 1,500 square feet) uses the plant filter in one of the two larger greenhouses. Below is a description of the two large greenhouse plant filtration systems.
First Stage: The first filtration stage uses plants in the vats. Our plants of choice for this stage are hornwort (Ceratophyllum demersum), a rootless floating plant, and guppy grass (Najas guadalupensis) that we stock in most of our vats. Both are rapidly growing plants that do not suffer a significant slowdown in growth during the winter. With hornwort, we keep a ten to twenty inch sprig with new growing tips in each vat. About once a week, the sprig is pulled out and the older end pruned and discarded. Guppy grass doesn’t float and is used sparingly since it will fill a vat from bottom up, interfering with feeding and netting. In addition to the hornwort and guppy grass, there is a group of volunteer plants often present in the vats. The group includes several species of algae (mat and hair algae primarily) and duckweed (Lemna). We don’t encourage these plants, especially the duckweed, because it interferes with feeding and netting, but they are present and almost impossible to eradicate. These plants feed heavily on the ammonia waste products of the fish.
Second Stage: The second filtration stage is a complex of plants in our floor gutter. This complex consists of hornwort, algae, Bacopa caroliniana and duckweed. Again the algae and duckweed are volunteers that we don’t particularly encourage but tolerate out of necessity. Bacopa is a native plant with an emersed growth pattern. It forms floating mats and grows up on to our wooden walkways. Its primary deficit is a tendency to go into dormancy in the winter and ceasing to grow. The floor gutter in each large greenhouse is thirty by eighty feet in area and averages six inches deep. It is walled on three sides and is dammed at the open end by a thirty foot long, six inch high wall. The water falls over this wall into the plant filter.
Third Stage: Third and final stage of filtration is a sump at one end of each greenhouse. This sump is about thirty by seven feet in area and several feet deep. The sump is populated with Red and Black Mangroves and Oja Santa. Mangroves produce thick, fleshy leaves that require heavy feeding by the plant on the fish wastes in the system. Oja Santa is a member of the pepper family (Piper), which grows rapidly and produces large leaves used in Central American cuisine.
We tested another plant, Dieffenbachia, but soon considered it a failure not because it didn’t work for filtration but because it has a toxic to human skin sap. If you are interested in it, here’s a blog I wrote about it: http://goliadfarms.com/monster-plant-dieffenbachia-species/.
Collectively, the three stages of plant filtration maintain zero levels of ammonia, nitrate, and nitrate in the system and provide us with an addition source of revenue in the form of plant sales.
Chuck Breiter says
I have gone to all planted aquariums with no other filters. I discovered this after doing some research . I read Ted Coletti’s article in TFH a few years ago, that stated that NITRATES harmed Mollies and that was why they need salt. It wasn’t because they were brackish.
My water came out of the tap with nitrates at 11 ppm. I failed miserably with Mollies. I started experimenting with plants because they offered grazing of microorganism and they eliminated my nitrate problem. I expanded on this and run my 20 tanks without filters including Discus. I have started speaking at clubs and pet stores.
I’m not a chemist and Ted is knowledgeable, but if salt corrected nitrates then marine aquarists wouldn’t bother testing for it. Mollies are very sensitive to ammonia (in the form of nitrogenous waste), which we usually measure via nitrates and nitrites. Plants need nitrogen, which is why plant filtration works. Like you, I use exclusively plant filtration.
Aaron Price says
How many mangroves do you have per vat? The articles I’m reading say they’re slow growing and don’t absorb miraculous amounts. Is it because yours are full grown?
Charles Clapsaddle says
We have both Red and Black Mangroves. Neither are slow growing for us, but we have lots of direct sunlight in our greenhouses. Red mangroves reach 14 feet in height and spread within 4-5 years. Black mangroves are smaller, but also grow fast.
The mangroves did a great job of ammonia control for us, but we’ve started phasing out both species in favor of other plants, primarily Oja Santa. We are keeping only a handful of Red Mangroves because the plant is host to a moth that has a nasty stinging caterpillar locally known as asps. We’ve also reduced the number of black mangroves because their leaves are the perfect size to clog up our overflows. The mangroves and oja santa are currently planted in between vats. We also use hornwort in most vats and guppy grass in some, the emersed plants like mangroves and oja santa do most of the work. We’ve used Pothos (house ivy) successfully in the past.
Thank you Charles for the reply. I just saw this. The oja Santa… is that the aromatic herb plant? How did you use Pothos? I had some of it emersed in one tank one time clipped on with a clothes line clip but found the roots that were growing didn’t look very attractive. For the plant filtration do you have to add any potassium or trace elements for pothos or whatever plants you’re using to grow well? I know they’ll get nitrogen and phosphorous from food and fish waste but I’d think the others would be missing and needed. What made you try to oja Santa plant (if we’re thinking about the same one). How’d you discover it or what’s the criteria you look for before you test one out? It seems like an unusual plant.
Charles Clapsaddle says
As to Pothos, I simply dangled the cut end in the water and taped the growing end onto the stand. I had a 30 tank (10 gallon) recirculating system and placed the plants in a couple of the tanks. The roots aren’t very sightly.
Yes, the herb from Central America. Trying it was an accident. I bought some to plant along a water course. The leaves sell for $1.00 in Houstona and Austin. I placed one in the floor gutter of our greenhouse and it grew better than the ones outside.
We don’t add anything for the plants. We feed our fish heavily and their waste seems to provide everything the plants need.
We constantly look for plants that might work better than what we are doing. My favorite plant is water hyacinth, but it is illegal in Texas. When our hatchery was in New Mexico we used it exclusively.
Jacob Johnston says
As you continue to experiment, I would suggest Monstera Deliciosa (untested) or Monstera Adansonii (what I am using). Adansonii definitely produces long, branching roots from each leaf node which thrive submerged in fish water and suck up ammonia like crazy. I’m new to fish keeping, but I love plants so I put a cutting in my only tank as soon as I got it (15 gallon – can’t wait to dive further into the hobby) and just discovered incidentally that I never have ammonia, nitrites, or nitrates despite heavy stocking and generous feeding. It’s amazing because it’s only about a foot long and has 5 modest leaves. For a 15 gallon it’s surprisingly stable. I put the cutting in there to grow the plant, and had no expectation that it might take every bit of nutrients to the extent that I now must fertilize in addition to avoiding water changes so my aquatic plants can grow. Now that I have a house and more space, I’m going to experiment further with you as inspiration.
Charles Clapsaddle says
My all time favorite plant is water hyacincth (Eichhornia crassipes). It is a floating plant with a large batch of very fine roots great for killifish and tetras to lay eggs in. When our hatchery was in New Mexico we used it. Unfortunately, it is illegal in Texas.
Keep working with plants. They are wonderful filterers and also condition your house air.
Zachary SCHWETER says
I love the look of the Mangroves in the green house as trees. I live in NYC and I am very successful with Pothos and Bamboo – but want to try a “tree” like plant. What would or could you suggest that I experiment with?
Charles Clapsaddle says
Zachary, Black Mangrove is much more manageable than Red Mangrove. Having said that, two of us spent two days relocating two Black Mangroves. We had to severely prune them to move them. Fortunately, mangroves are storm tolerant and have to often recover from tropical storms, so they are recovering nicely in their new locations. My all time favorite plant for plant filtration is Water Hyacinth. Unfortunately, it is illegal in Texas. Bacopa is another very good plant. For submersed plants, I like hornwort.
Kevin Wai says
I have never had success with hyacinth indoors under artifical light. Any ideas how I can make that work??
Charles Clapsaddle says
I’ve never tried water hyacinth under artificial lighting. But, I suspect very high intensity, full spectrum lighting on a 16 hour day/night cycle would work. I wish I could advise you better on artificial lighting, but it’s been too long since I used any and there have been great strides in lighting including LED lights.