Howdy!
I have no experience with that Philodendron . . . I have never heard of it. But I have and have had many aquatic tanks with aroids and other aquatic plants. I prefer to use tanks that are far larger: at least 35 gallons. They tend to need less maintenance and fewer water changes. There are three kinds of tanks that I do.
Type I. I start with an empty tank, and put down a layer of very rich potting soil; usually an inch or so. On top of this I put an inch or so of clean fine sand, which I have rinsed VERY well to remove any salts. The sand will keep the soil from muddying the water. I then arrange my wood and rocks. I then fill the tank, using a large dinner plate on the bottom to prevent the water that is being poured in from displacing the sand and liberating the soil. Once the tank is full of water (to about two inches from the top, I put in a sponge filter and the heater. I plant once the water is clear and up to temperature. This is a good way to grow most aquarium plants.
Type II. I use an empty tank with a good lid. The tank should be broad, with a lot of surface area. I put in about four inches of water and a powerhead that keeps the water circulating at a good clip around and around in the tank. I also use a heater to keep the tank around 75 degrees F. In the bottom I use small bricks or tile and I put in potted aroids, with the pots set on the tiles/brick/rocks. This allows the roots to grow out of the pots into the water, and I can put different pots at different depths depending upon how wet they want to be. The lid will keep the humidity high. This makes really happy rheophilic aroids, like Bucephalandra, Hottarum, Schismattoglottis, and Anthurium amnicola. Aroids like Annubias and Cryptocorne will bloom if you completely submerge them for a week or so, then drop the water level slowly back to where it was over a few weeks.
Type III. Ten gallon or larger with potting soil on bottom, with water filled to the top. This is good for Pistia, Lemna, Wolffia, and Spirodella.
Have fun!
Christopher
