To summarize: and thank you everyone! This year i'm going to try a mix of all these. Light weight Pine cones Pop cans recyclables, crushed or not, including empty coffee cans, plastic containers, solo cups, etc. (not for food growing) Upside down pots PEAT pots Styrofoam – put in pantyhose to contain Colanders upside down Floral foam bricks Pool noodles - cut up Mulch Charcoal – without chemical treatment Straw (might soak up nutrients away from plants) Paper rolls – TP or paper towel (breaks down fairly quickly) Old golf balls (other balls?) Heavy Rocks Broken ceramic pots or ceramic pieces Plywood rounds cut to size Branches, pieces of wood tips: - Good idea to place landscape fabric between some of these non organic fillers before soil on top - If you are growing food, stick to organic matter

i would not put cattails in there --- there are lovely native plant mixes of tall grasses and wildflowers made specifically for detention areas. a detention area when planted properly makes a beautiful wildflower garden. and the native plants are an asset to stormwater control and water quality. their extensive root system helps dry out the bottom. do an internet search on "rain garden" there is tons of information out there.

Nothing beats going through the garden! I especially like the purple flower standing tall above others in the last picture of your post. I wonder what it is? Thanks for sharing your wonderful experience! Nancy

The tag says the 4"x6"x12' #2 0.15pcf micronized copper azole compunds . I didn't even think about if there was marine grade 4x6, did I screw up and use the wrong pressure treated post? That's my question "what to treat them with" or if I even need to? I figure the new piers are good for now but it might be good to seal the old piers? This little pond gets low every year or so, so I can seal them if need be later.