My backyard , Seashore Paspalum, is suffering from weeds ( Dallisgrass like crabgrass)

[bbright]

I'm really new in gardening. I thought that all the green is good for my backyard.
Recently, I recognized that my grass in the backyard has been invaded by weed, Dallisgrass and Bermuda grass.

At this time, killing the weed is priority to me. I'm trying to pull the weed, but it's too much to get rid of all with that way. I need any other effective solution to remove the weed.

So far, I didn't use herbicide or chemicals because some chemicals may kill not only the weed but also the grass.
Do anybody know effective solution for seashore paspalum in order to get rid of the weed?
Also, Do you know how to remove Bermudagrass from the seashore paspalum?

[Dchall_San_Antonio]

We need to know where you live. Do you remember that spot in your profile where it asks for your location? We're expecting something like Costa Mesa or Big Bear Lake. Southern California has every climate and soil type, so we need to really know where you are. And if you are in a community along Interstate 5 or the 405 in LA, it would help to know if you are east or west of the highway. Also if you can estimate the size of your yard and put that into your profile, that helps us to help you without asking these up-front questions.

Having said that, seashore paspalum is a rare turf type in general. The only places I've heard of it being used are some locations in FL and in San Diego county. I'm going with San Diego for this reply.

Killing bermuda grass is hard to do even in bare soil. Bermuda is a sod-forming type of grass that spreads via both stolons (above the ground) and rhizomes (underground). Trying to kill it without damaging the surrounding grass is going to approach impossible.

Killing dallasgrass is easier because it is a bunch grass that spreads out from a central spot. Dallisgrass can be killed with a strong dose of baking soda. I am going to try a new application technique this year using a solution of baking soda in water daubed onto the weed with a sponge. The old method involved spraying the weed with soapy water and then dusting the baking soda on it. The sponge method will be a LOT better if we can figure out how much baking soda to put into the water. I would go with almost a paste consistency daubed on the weed. The baking soda will likely damage the seashore paspalum, so if you try the baking soda, try to keep it on the weed.

For the long term, the bermuda will end up being the dominant plant if all you have is the seashore for it to mix into. St Augustine, on the other hand, will dominate bermuda and take over the yard from both the bermuda and seashore paspalum. St Aug can still get dallis in it, but it is controlled easily. If you are interested in switching over to St Augustine, I can help with that. St Augustine is appropriate for all of SoCal with the exception of the mountains above 3,000 feet (horrible soil and too many trees up there). St Augustine has a much different look and feel than other turf grasses. Whatever you do, don't replace paspalum with Marathon type fescue sod. The bermuda will take that stuff over easily.