Hello, Good questions as sometimes it is not made clear what and where items are to go.
1- the underlayment is meant to protect the bottom of the liner, so no it does not need to match the liner.
2- Yes you can fill both bags or save one for later when the first one falls apart because of old age. Fill it with anything that will allow growth of bacteria. We sell bio balls, they have lots of holes. Lava rock is an urban legend, it does not have enough holes to create surface area for the bacteria to grow. Bacteria will grow on it just not enough to do a good job.
3- roots will grow into the mat. You could use a milk crate and cut a board to fit the falls and cover with plants. Or take the filter and bottom support out and fill with rock and plants. you could than use the bags to hold barley straw in the pond area.
4- You want the bacteria to grow in the falls. As the water flows over the rock or balls or filter material the colony of bacteria will filter out and eat the nutrients that have been created by your fish. You can also add it to the pond area to grow on the rocks in the bottom of the pond. Some of these tell you to add it to the skimmer area so that the pump will pull it up to the falls. We tell out customers to fill the falls with water and cover the tube where it inters the falls so the water stays in the fall area. If you have a check value it will keep the water in the falls. Now that you have water in the falls sprinkle the bacteria into the water and let them set up house on the filter, bio balls or rocks how ever you decide to fill the falls area for two hours. After this two hour set up time you can start up your system and enjoy. Remember to follow directions and keep this colony alive because this is what helps to clean your water. Plants will also help. Up to 64% of the open water should be covered to help keep the algae growth down.
5- Gold fish are hardy and good to start a pond but donÂt put in to many before your plants are ready to clean the water. If you are on city water give it a few days to evaporate the chlorine. If on well throw them in when you are ready.
6- I have not dealt with plants yet but I believe it is from the crown, Water plants just need something to anchor to.
I have seen them just in pots of rock so that they could be brought in when the weather changes.
Hope this helps,
Michelle
www.ncpond.com

Here is a link that might be useful: NC Pond site

1) No, just a little beyond the water level.
2)My favorite is Savio Springflow bio media, or polyester strapping. Whatever media you use make sure it is light weight for easy cleaning.
3) You can make a grate, or use laundry baskets to keep plants in. I made a grate for my filter. It is actually two vertical grates with filter pads inside. Designed so I can "Shake" off debris when flushing the filter.
4) The pond bacteria.....Add it in the water and it will settle on hard surfaces. Hopefully on the bio media.
5)Plants can go in almost immediately. Add a few goldfish at a time(over weeks and months) to let your filter catch up..
6) Make sure marginal plants have their crowns above water level. Water Iris can take being submerged a few feet. I have plenty of water and regular garden plants anchored only by edge rocks that overwinter and survive every year.

Regards,

Lisa

So I can just add the marginals to the edges of the pond using rocks to anchor them? From what I've read some floating plants can be invasive. Are some marginals the same way? Which would I want to avoid if I don't plant in pots?

you can have such a beautiful pond if you DONT have fish

everyone overpopulates their ponds with fish and their poop causes so many problems

if you must get fish, wait a few weeks for the bacteria to grow and set a limit of only having a few...and dont overfeed them. I have fed mine only once this year, they are nibbling on algae and roots of plants for food....all fish still nice and healthy

and dont forget about chloramine if you use city water, it will linger in the water for a few weeks and kill any fish you put in there.....unless you treat the water. the chlorine disappears in a few days

Hi,
Plants I have had that ran like crazy- Water mint(mentha aquatica), Pennywort(hydrocotle), water clover(milfoil). If you get anything that grows by rhizome it will sneak around on you. Depends on what you want whether you will be happy with where it spreads. One thing to keep in mind with the plants is if they do not survive the winter you will want to be able to pull out the roots so they are not adding to the bio load. I tend to plant them in pots for the first year and if they survive then I take them out of the pots and let them go.

I think I'd like to have one waterlily, one or two sweet flags, and one dwarf cattail. I'd also like a couple of different submerged/floating plants. I don't want anything that will get away from me. Can the plants that stay on bottom be planted in pots? I am not really sure about anything regarding plants. I need to do some more reading on the subject. Thanks for all of the replies. All of you have been awesome answering the pond newbie questions.