On the other hand, I've had anemones for years and they've never come close to a powerhead except on one occasion with a new addition.

Low maintenance could be a few things... The fewer the fish you have, the lower amount of nutrients that get added by feeding. If you have only two clowns, a feeding once a day or every other day should be enough. Have a skimmer if possible or macro algae to help extend the amount of time between water changes. If you have no corals, then your parameters can be slightly more lax. When introducing anemones, keep water flow light for a few days and slowly increase it so you give your new fellas a chance to find a new home. Introducing it close to or on your rockwork would be great and if you can, get some that are already attached to a rock so they don't float around as much or have them in a container with a rock that it can attach to. A sand bed is more o a personal preference but I've worked with sandless and after awhile, they get boring. The addition of sand adds a lot to a tank but like I said, just a preference. It doesn't buffer all that much and if you're not feeding much, it wont be much of a hassle for cleaning.  

Regarding sand, its presence can help create a stable tank if certain principles are understood and followed:

1. The sand we use is made of Calcium Carbonate(CaCO3). We don't hear it said anymore but in the early days we often spoke of the "buffering capability" of Calcium Carbonate sand. Buffering is the ability to keep the water chemically stable. In other words, Alk, Ca, Mg and pH levels are able to be more constant when CaCO3 sand is used. Today though, so may hobbyists are keeping animals with such a high demand for Alk, Ca, Mg, etc., that the sand alone cannot keep up with the demand. Luckily we know how to test and then dose those components to keep things stable even where no sand is used in the system.

2. Some types of CaCO3 sands and the depth of the sands can have a greater influence on chemical buffering than others. At the bottom of the sand bed we want a low Oxygen climate to exist. This a lower pH zone where CaCO3 can dissolve, thus providing Alk, Ca, Mg, and trace elements for the growth of the animals above. A deep sand bed is more certain to provide this low pH layer. An inch of typical sand is not deep enough. Deeper sand beds do the job, but there is a simple trick to this that is not that well known. The trick is to use a 1/2" layer of smaller particle CaCO3 sand known as Oolitic sand placed on the bottom, with 1/2" of regular size sand on top. The low pH zone exists at the bottom of the Oolitic sand. This provides the buffering while allowing a sand depth of only 1 inch. 

3. Some types of sand are better at encouraging the growth of animals that have a beneficial effect on tank bio-stability. These are animals such as bacteria, bugs and worms. Many many years ago, one of the pioneers of this hobby pointed out that some animals like to live in fine sands while others prefer living among larger particle sands. If there is one thing about sand that I have found is better at keeping a reef aquarium stable, healthy and as low maintenance as possible, it's this.

If you have ever visited with me and seen my systems, you will know that this is only one of the things I do to ensure my systems are as low maintenance as possible. 

Aloha,

Mark