Please keep in mind that Texas cichlids, Jack Dempseys, and jags are much different than African cichlids, all the way down to their diet needs.
Central and South American cichlids will prefer softer water from what the Africans need, they also are carnivores... where Africans tend to be heavy vegitarians.
The central and south american groups of cichlids do as much digging as the africans, so to hear about the plants is normal. The africans tend to eat the plants, the fish you listed above tend to do more digging than eating.
One other good food option for the dempsey, texas, and jag cichlids is Formula 1 frozen food. This particular food supplies most of the nutrients they need for a well rounded diet, and also contains garlic, which will help to strengthen the immune system.
Mutt, have you checked water quality? Even though the water appears clean and the solid waste is not visible, there is also liquid waste in the water, so checking water params frequently will be of huge benefit to you and your fish. Water params will help you to alter the maintenance schedule as your fish grow.
I'm glad you're aware that these fish will outgrow a 10 gallon tank, though I never suggest even starting them in something that small because they grow so rapidly. The other thing I'll warn about the 10 gallon tank is in topping it off instead of doing actual water CHANGES. Water evaporates, waste does not. If all you do is top off the tank without checking water params, then you can very easily concentrate waste in the water, making it worse by adding water, and harder to get under control. These fish are all prone to illnesses induced by high nitrate levels. Now would be a good time to start planning a larger tank, and if you wish to save some money, go LARGE right away, let the fish grow into the tank. Those fish are going to top out around 8 - 10 inches each, so a tank of well over 100 gallons is going to be needed soon enough. A healthy jack dempsey will more than double in size in 6 - 8 months or less until they get into the 6+ range where it slows down until the fish is full grown.