For the past two years, I've been growing Aldrovanda in my planted aquariums; I started with 5 strands, now I have more than 100 (and I've traded or given away about that much also). The Aldrovanda I grow is from Darwin, Australia, it is tropical and does not require dormancy. I received it as a gift from a plant biologist at the 2005 New England Carnivorous Plant Society (NECPS) show.
I have two aquariums that I grow Aldrovanda in, a heavily-planted 'high-tech' 55-gallon tank, and a 'low-tech' 29 gallon tank. I'll go over the 55-gallon tank first, here's a picture:
I use a 4 x 55-watt compact fluorescent light fixture, with parabolic polished aluminum reflectors, to light the tank. Lights run 10 hours/day.
I use an Eheim canister filter, with a spray bar outlet. It's located underneath the aquarium in the stand. This filter creates gentle water movement and the outlet is directed not to send the Aldrovanda to the bottom.
I inject pressurized CO2. The water I add to the tank has a pH of about 7.5, I lower the pH with CO2 (which makes carbonic acid when dissolved) to 6.5. Here's how the setup works: water is sucked into the canister filter, and directed to a CO2 reactor behind the tank:
The water comes from the filter into the top of the reactor. The CO2 line comes in to the reactor also, and bubbles are generated at the bottom of the reactor. The water flows down, the bubbles go up, so you get complete mixing of the CO2. The water then flows out the bottom of the reactor and into the aquarium.
The CO2 is from a pressurized tank:
The regulator for this unit has a solenoid, and is controlled by a pH meter:
This is the pH probe for the unit, which is in the aquarium:
The pH is constantly monitored. When it rises above 6.5, the pH meter turns on the CO2 until the pH drops to 6.5 again. This whole unit allows me to get very a high CO2 concentration (but not too high to harm the fish).
I use Eco-complete topped with pool sand as a substrate. I have several types of aquatic plants growing in the tank (swords, ludwigia, rotala, moss, stargrass, mayaca). The fish here are columbian tetras, cardinal tetras, corydoras and hatchetfish. To control algae, I have several fish: a siamese algae eater, otocinclus, as well as cherry shrimp and ramshorn snails.
I change half the water weekly (20 gallons!). I also add fertilizers: potassium nitrate, potassium phosphate, and plantex (a micronutrient mix). I also add additional sodium bicabonate to increase the carbonate hardness; and magnesium sulfate and calcium chloride to increase the general hardness.
This whole setup cost me about $1000, probably more I set it up initially only as planted aquarium, I threw in the Aldrovanda on a whim. The Aldrovanda grow like crazy in this tank, they are constantly producing flowers and cover most of the top of the tank. Here's some pics: