Have you tried placing a plate or cup in the tank while you fill the water. I find this helps me when plants want to constantly uproot.
In my experience close to a month before they are firmly rooted. But it depends on the plant, stem plants tend to root deeper and faster, maybe in two weeks. One trick that I've seen is to cut a soda bottle in half and put holes in it to let the water drain out. As the water level rises so does the soda bottle so you don't disturb the substrate.
I just tie one end to a small rock so as to sink to the bottom of a pail, then I set the pain on the rim of that tank, toss the rock with tubing in and siphon away.
richie_brave;10647962 oh said:Yes, both of those plants will grow faster emersed, but they are both fast growers anyway, so you probably shouldn't go through the trouble of stripping your tank down to do a dry start. Dry start method is not typically used for stem plants like bacopa because they can take a long time to adjust to submerged conditions - and they grow very fast underwater anyway.
I like to pour water over a block of filter foam when I do water changes, but any of the suggestions in this thread will do.