Gary, have you read anything on bog gardens? I realize you want a more liquid environment but it might give you some ideas. Freds bog used to be on GWs bog forum but I think he left. I saved his original post though if you can't find it.

Perhaps I am just missing the point, but if they are aquarium plants why wouldn't you just plant them as you would in an aquarium. That is: plants are 'rooted' in fine (attractive or not) gravel. It has been 60 years since I had one, but isn't that what we did back then anyway?

I was initially going to suggest kitty litter in the same way. It sends up a fine dust, but that will wash away.

chas 045
Most of the carpet types require a lot of pruning ,otherwise they tend to run particularly if they have competition for light. i know they won't make it through winter so need a way to renew the substrate in early spring. Since this will be 4x5 feet BIG problem lol
Even with out the geometric designs will require a LOT of maintence . Have done this in aquariums but a LOT more control in the glass boxes lol.
Turface is a type of clay litter but is fired ,so much more stable. Crushed lava rock would be good but particle size is too large and neither provide enough nutrients for lush growth . canadian peat and top soil are perfect but color the water. gravel has the same problems and cost much more. Whatever I use will have to be replaced in spring to start growth over.The tiny pots in rows would be great for contorling which color grow where and could be individually removed I realize I'm setting up a HUGE maintence problem but want to try ?? lol
sleepless Well it definitely wouldn't be a bog as these types do best in around 7 pH which my rainwater will provide .I'm intending to use a "purge system" for filtration. Obviosly the water will have to be crystal clear or the effect would be lost Thanks for the help
gary

Just for my own curiosity, how often would you need to purge it to avoid algae blooms? How deep do you want it?

I tried to look up more info but got stuck in greywater or sewage treatment with a search for constructed wetlands or marshes. That wouldn't seem to fit in with your clear water. The common substrate there is gravel, sand or 1/2 to 1 inch rock. How about Schultz pond planting medium? I tried using that for my pond plants but the critters kept dumping it into the pond and the pump picked it up and it destroyed the pump motor. I think it is similar to the Turface except for size. Perlite was suggested several times and I have had success with it in a number of experiments, just not a marsh. It is cheap, easy to locate and fairly easy to handle. Easy Green balls are porous fired clay. They are 1/2 inch in diameter and are used in hydroponic gardening. They are very light when dry and come in 10 pound bags, about 1 1/2 to 2 gallons in volume. The bag I have left is partly used so I can't be sure. I think I paid about $12 a bag but that might be off. There aren't too many hydroponic suppliers in this area and it has been a while.Once wet they wouldn't hurt the pump.

Would your purge system equate with the hydroponic ebb and flow system? You will have to feed the plants somehow.Is a pump out of the question? A vertical hydroponic design might be very dramatic with your selection of plants but that would require a pump.

Do you have any links? I seem to keep going in circles. As always I am interested in learning even if I can't create the system myself.

Hi
In my case a "purge system" is a connection to rainwater runoff from the roof carried by underground pipes ,overflow goes into a gravel area . The "marsh is about 10 years old and in the past I grew mostly emergent tropical foliage . I grow the carpeting type plants in aquariums with degrees of success and since I was reworking the marsh thought it would be interesting to not only attempt them there but with the added twist of a geometric garden BUT underwater. They are VERY finicky and require constant management even in a controlled area of an aquarium. In order to "carpet they need a fins substrate so they can root horizintally other wise they tend to bolt for the surface.
I ran a "vertical hydroponic design for several years in the GH. I called it a "seepwall" trying to emulate those areas in tropical forests . Just short of a water fall. While it was gorgeous it was a nightmare of management!!lol. I no longer heat the GH overwinter so it's become very limited as well as the reservoir developed a leak. It now serves as a semi/aquatic terrarium.
Back to the "marsh" lol It will be 4x5 approximately 15 inches deep to allow enough water for the contained emergents so will have an area of around 2x5 feet for the carpets I feel that it can serve between early march to late oct . but since it will be depleted by that time need an easy way to remove the substrate. In aquariums I use a mix of "blackcow and topsoil with a light coating of fine sand. but obviously wouldn't work outdoors though it might if there's an easy way to remove it. Obviously it would pass right through a screen though I'm thinking cheesecloth but would probably rot.. Just another one of my crazy ideas that require total failure to make me move onto the next crazy idea!!!. Thanks for the help!!! gary.

What about using a permeable (woven) tarp under the substrate, similar to greenhouse shade cloth? It comes in various densities.It is designed to withstand all sorts of weathering. Then there is always heavy duty landscaping cloth. Does it come with reinforcement or could you add reinforcement?

Hi
Sounds like a good idea!! Have been experimenting with 3/4 inch square pots using rock wool as a media . Would make changing out very simple with infinite adjustment as it grew . Problem with that is the number of pots for an area that size!!. Going to start with "stripes " alternating between red and green with a yellow center. If it wotrks will go for a more elaborate design. Another problem with the area is it's in the shade of a Cassia tree
Though high above the water might interfere with enough light. In aquariums they are VERY demanding Another problem is that I don't have near enough plants to fill it !! lol I could start small until i see if it's going to work. Thanks for the suggestions !!! gary