sorry typo..it is gravity fed!
Rudee H, could you post a picture of the pond/filter box? It may be easier to help you if we can see the problem.
Can you put Flower pots on it and around it.
Actually you can make a hollow "fake rock" out of hypertufa and customize the size to accomodate the size of your filter box. hypertufa is a product made from concrete and instead of using sand, you use peet making it lighter and still strong. I do not remember the ratio of cement to peet but I'm sure you can google it, it's a fairly common item. Just make a wooden box to fit over your filter fairly loosly and cover it with a couple plastic lawn and leaf bags, (to help you get it off the wooden structure after it's dry) or you could decide to leave it On the wooden structure...if you aren't going to have to lift it that often or have someone to help you lift it when necessary...cover it with the hypertufa mix and shape it into your artistic vision of a rock/boulder... you can even use concrete stain when you mix the hypertufa so that the boulder is "brown, or reddish" or whatever...let it dry for at least 24 hours before trying to take it off the frame...
Also...if you want a "mossy" rock...after it's dry and in place....find some moss growing around your area...a piece the size of a 50 cent piece is all you'll need...put it in the blender with a quart of butter milk and mix until smooth....use a paint brush to paint it on the rock and then use a spray bottle to mist it lightly with water several times a day for a week to 10 days...and the moss should start growing in the crevices of your new rock...voila! a new Rock covered filter box...
ok thanks to you all. I am going to take a picture and post it later or tomorrow but the Hypertufa sounds a great idea!
There are hypertufa tutorials listed in Google.