Seems like you *should* be fine- aluminum is non-reactive with most "garden" chemicals. I'm in the process of making a 48" x 30" terrarium from recycled aluminum sheet- It's cheap light and fairly portable. I got the sheets at the recycler's where it's by the pound. I think its not used much because new aluminum is rather expensive & used is rather hard to find. At least in 'put a plant in it' type shapes.

I'd agree with most of what everyone else is saying here. Most of us would give our left reproductive organ to own a site like that. ; ) As to management, there are several things I'd encourage: 1) Identify what you've got using wildflower guides or other resources. Your local agriculture extention office can help you identify plants (or you can post photos of them and we'll do our best). 2) Eliminate invasive exotics (like the autumn olive - if that's what it is.) 3) Eliminate Nutrient (fertilizer) Runoff! Your description already suggests a high nutrient load. Algae and cattails are a sign of too much nitrogen and phosphates. (but don't feel you need to remove them, as they are natures way of trying to bring the system back into balance). 4)Grasses/sedges are good. The aesthetic americans have developed of wanting an articifically mowed or landscaped area is a relatively recent invention. It derived as a status symbol. There is a strong new aesthetic developing which values more natural looking environments. You could choose to be in the "in" crowd and keep your grasses. 5) Selectively reintroduce wildflowers native to your area. Here are some species to consider: Iris virginica, with spectacular blue flowers. Lobelia cardinalis, Cardinal Flower Lobelia siphilitica, Blue Lobelia Rhexia virginica - Meadow Beauty (pink) Eriophorum virginicum - Cotton Grass. Yes, another grass, but has tufts like white cotton that look fantastic. (You might have seen it at cranberry glades) Eupatorium purpureum, Sweetscented Joepyeweed. HUGE plumes of purple fragrant flowers that butterflies love. Vernonia noveboracensis - New York Ironweed. Dark Purple flowers in late fall. 6)CREP(Conservation Reserve Enhancement Program). Believe it or not, you may be able to get money or reimbursement for certain restoration and preservation of your wetland. This site can tell you more: http://www.fsa.usda.gov/dafp/cepd/crep.htm 7)OPTIONAL/ADVANCED - One way to encourage a healthier landscape is to burn the meadow area in late winter / very early spring. There are agencies that can educate you on the proper way to do this, but don't attempt it yourself without experience or assistance! The general concept is to choose a low fire risk day in late winter. Notify the fire Department. Mow or plow around the edges of the site to create a "buffer" and wet the edges down. Then, burn from the outside in (so it stays in the circle). I hope all this is helpful to you. If you do choose to enhance the site, please send photos of the progress. I'd also want to add my voice to the others that suggest that doing nothing except appreciating it, is also a valid and worthwhile option. Here is a link that might be useful: A Native Plant Nursery (Hyla Brook)

Grasses and sedges are relatively cheap and/or can easily be grown from seed. In the fall we make the rounds of some of the local native wetlands and collect seeds. Also check nursery year-end sales. Check with some of your local native plant experts and they may be able to put you on to sources. In the US, many county cooperative extension service offices have master gardeners that can also give you ideas.

Plastic bag is fine, I've done it. Holes are better towards the top if at all, just make sure the mix stays wet. Potting soil in the mix is not so good, peat sand is better. These guys like acidic nutrient poor conditions ... although the chadd's ford will probably like your mix.